Squirting toothpaste onto a toothbrush is so second nature that it’s unlikely you’ve put much thought into the words behind it, but we’re here to tell you that there’s a word for almost everything. That little wavy blob of toothpaste is officially called a “nurdle.” While the word seems like it could come from either a nursery-school rhyme or a sci-fi saga, it’s no joke. In fact, it was once at the center of a courtroom dispute between toothpaste manufacturers — high drama indeed. 

The origins of “nurdle” didn’t begin in the dentist’s office. In the 1960s, “nurdling” was a spoof pub game invented by absurdist British comedian Michael Bentine, and in the sport of cricket, “nurdle” applies when someone scores a run by gently nudging the ball to a vacant area of the field. A more modern definition for “nurdle” is that of a small pellet of plastic used to manufacture larger plastic products. This definition is probably most closely related to toothpaste usage, as it refers to a small portion of something.

But as we transition to dental care, it gets a bit murky. “Nurdle” is a nonsense term without a clear etymological origin. It’s been proposed as a spelling variant of “nodule,” which is a “small rounded lump.” This can give us a loose connection to “nurdle” as a small lump of toothpaste, but it’s still just conjecture.

Perhaps the earliest known printed instance of “nurdle” as toothpaste was in a 1968 advertisement for the now-defunct brand Vote. The ad included the tagline, “A nurdle a day keeps the dragon away” (with “dragon” implying “bad breath”). Decades later, in the 1990s, the American Dental Association adopted “nurdle” in its literature to explain the proper amount of toothpaste to put on a brush. The ADA likely brought “nurdle” to the forefront of the dental industry; however, we know the organization didn’t coin the word, as it appeared in ads decades earlier.  

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But the word might never have been brought to public attention if it weren’t for a courtroom battle between two major toothpaste manufacturers: Colgate-Palmolive Co. and GlaxoSmithKline PLC (which produces Aquafresh). They were fighting not over the word “nurdle,” but over the right to use an image of the wavy blob with tricolored toothpaste and either the words “Triple Action” (Colgate) or “Triple Protection” (Glaxo). Advertisements are worth big bucks, and the companies reached a confidential settlement over the nurdle imagery in 2011. 

English is full of rules, but it’s also full of exceptions — even in spelling. Just when you think you’ve got it right, you run into a word with multiple “correct” versions. Some of these differences come down to geography (British English vs. American English is behind many of these distinctions), while others are the result of the natural evolution of language. Either way, in many of these examples, both versions are accepted by dictionaries; for others, there’s a clear correct version, depending on context. Bottom line: Choose the one that feels most natural or aligns with your audience. Consistency is the priority when both spellings are correct.

Many of the differences between British and American spelling exist because of Noah Webster’s A Compendious Dictionary of the English Language, the first American dictionary, published in 1806. In the spirit of the newly independent United States, Webster sought to liberate Americans from British spelling. He promoted more efficient spelling as a statement of patriotism. Thanks to him, “colour” became “color,” and the letter “u” dropped from many other words, including “favourite,” “neighbour,” and “labour.”

This is another classic divide between American and British English, thanks to Webster. In the U.K., the French-influenced “-re” spelling reigns, but in the U.S., Webster advocated for a spelling that matched pronunciation. One notable distinction here: Both “theater” and “theatre” are acceptable in American English, but each may carry slightly different connotations. “Theater” is used more generally, while “theatre” suggests a live performance or an academic context. So you might attend a Shakespeare play at a “theatre,” but catch a summer blockbuster at the “theater.” The same nuance tends to apply when the words are in the names of establishments.

British English uses “cancelled” with the double “l,” while American English typically goes with “canceled.” Strangely, both sides agree on “canceling” with a single “l,” but “cancellation” with two. Webster tried to drop an “l” — also changing “travelling” to “traveling” — in his efforts to make American English more efficient, even if it made things a bit more confusing.  

Yes, this distinction is thanks to Webster, too. Words in the pattern of “organize,” “recognize,” and “analyze” are always spelled with a “z” in American English, while British English prefers the “s” versions: “organise,” “recognise,” and “analyse.” But here’s a twist: Some British dictionaries also accept the “z” spellings because the words derive from Greek roots that use “zeta.” Still, it’s safe to use the “s” form in the U.K., and the “z” in the U.S.

“Doughnut” is the original, but “donut” is the modern, shortened version. If you prefer your pastries with a dash of tradition, “doughnut” is still deliciously valid (and even preferred in some formal contexts).

“Grey” is the preferred spelling in the U.K., while “gray” is more common in the U.S. and preferred by major style guides. Think “e” for England and “a” for America. Or just pick a favorite and stay consistent — spellcheckers accept both.

Both spellings are correct in both American and British English. However, the U.K. strongly prefers “likeable,” while the U.S. prefers the shorter “likable.” Both are pronounced the same, even if the missing “e” makes it look like the latter might be pronounced “lick-a-ble.”

The original spelling is “duffel,” from the Belgian town of Duffel, where an oblong bag of thick cloth was first made in the 17th century. “Duffle” is a newer anglicized variation that is now widely accepted.

In much of the English-speaking world, “chilli” with two “l’s” is the preferred spelling for the pepper itself. In the U.S., “chili” can refer to both the pepper and the stew. Meanwhile, “chile” is a regional variation in the American Southwest (especially New Mexico) referring to both the pepper and regional dishes made with the local chile pepper. (The proper noun Chile is the name of a country in South America.) These distinctions matter, so tread carefully, especially if you’re writing a recipe, food label, or travel guide. Just don’t confuse any of these with “chilly,” which has nothing to do with food unless it’s refrigerated.

“Omelette” is the original French spelling, and it’s the standard in British English. Americans often drop the last two letters and go with “omelet.” There are many common misspellings including some or all of these same letters, but these two versions are correct. Either way, you’re getting eggs.

Like color and colour, this variation concerns  that British “u.” “Glamour” is British, while “glamor” is the simplified American version; however, “glamour” still remains common in U.S. writing, including as the title of the American magazine Glamour. (The Associated Press also prefers the “ou” spelling.) The word “glamour” came from the Scottish word for “magic spell,” and survived in American English even after Webster’s campaign against the “u.”

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This distinction isn’t geographic — just confusing. Both “adviser” and “advisor” are correct and used interchangeably. Some institutions and companies choose one over the other, but there’s no major difference in meaning. Consistency is key — pick a spelling and stick to it. 

We’ve all been there — you run into someone you definitely know and you chat with them for a few minutes, but you’re wracking your brain to remember their name. Now it’s too late to ask because you might hurt their feelings. Well, it’s a good thing file formats don’t have feelings, because most people have no clue what “PDF” stands for — even those of us who regularly use PDF attachments in emails (and those of us who regularly forget to attach those PDFs to the email).

“PDF” stands for “Portable Document Format,” and it was conceived of by Adobe. In 1991, co-founder John Warnock initiated what he called the Camelot Project, which had a goal of making it easier for people to view, send, and print digital copies of documents. PDFs were created the following year, and officially launched to the public in 1993.

When you break down the acronym, the word “Portable” is arguably the most important. It helps capture the versatility of this technology, which is meant to make it easy to exchange files. The words “Document Format” are more literal in nature, denoting the fact that PDFs are a specific manner for saving digital files (as opposed to .doc or .mp4).

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This discussion may make you think about the names of other common digital formats, such as JPEG, PNG, WAV, and more. “JPEG” stands for “Joint Photographic Experts Group” — a committee that conceived of this compression method for digital images in the 1980s. “PNG” stands for “Portable Network Graphics,” and is mainly used for digitally transferring images or graphics with transparent elements. “WAV” means “Waveform Audio Format” and is reserved for saving and sending audio files — this abbreviates the first word rather than the first letter of each word.

So in the spirit of exchanging PDFs, go ahead and share this knowledge with anyone else who may be curious.

Whether you’ve considered it or not, you’ve probably chosen between the adverbs “especially” and “specifically” countless times. One of my favorite authors, Agatha Christie, illustrates this choice in her second novel, The Secret Adversary, in a few lines of dialogue:

Christie’s use of “especially” here adds emphasis (and a note of sarcasm) to the idea that a clergyman’s daughter would suggest something so outrageous. If you replaced “especially” with “specifically,” the sentence might still be grammatically correct, but it wouldn’t carry the same tone or effect. That’s because, while they appear in similar contexts and are occasionally interchangeable, “especially” and “specifically” are not true synonyms. They carry distinct meanings, so choosing one over the other can subtly shift the meaning of a sentence.

Consider this example: “Mary enjoys outdoor activities, especially hiking and kayaking.” This usage implies that Mary enjoys many outdoor activities, but her favorites are hiking and kayaking, because “especially” gives emphasis. Now consider a slight change: “Mary enjoys outdoor activities, specifically hiking and kayaking.” This swap of “especially” for “specifically” changes the meaning of the sentence because “specifically” implies that Mary enjoys those exact activities — hiking and kayaking — possibly to the exclusion of all others. The meaning has shifted from emphasis to precision.

This nuance is clearly reflected in the definitions of the two words. “Specifically” means “in a way that is exact and clear; precisely,” so it narrows the scope of the topic and draws boundaries. In contrast, “especially” doesn’t exclude other options, but its definition emphasizes it is “used to single out one person, thing, or situation over all others.”.

When deciding which adverb to use, consider your intent. If you want to give standout examples but not exclude other possibilities, use “especially.” (A mnemonic lurks in this advice, as the “e” of “example” matches “especially.”) You might say, “The kayaking handbook is useful, especially for beginners.” This suggests that the handbook is helpful to many people, but beginners will particularly benefit from it. 

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On the other hand, if you need to define or limit the category you’re talking about, use “specifically,” as in, “We need to hire someone with experience, specifically in leading kayaking tours.” This clarifies that the requirement is experience of a particular type. Understanding the subtle distinction between these two adverbs allows you to harness their full potential.