BO is casual, a little blunt, and often used when people want to talk about a bad smell without saying the longer phrase. It can show up in conversation, comedy, school hallways, gym jokes, deodorant ads, and word games.

In the May 29, 2026 NYT Connections puzzle, BO mattered because it belonged in the group SOURCES OF DISTINCTIVE SMELLS with AMMONIA, DURIAN, and WET DOG. The full puzzle breakdown is here: the daily Connections guide. BO was not a name, a music clue, or a two-letter code. It was short for body odor.

That little abbreviation made the clue trickier than it looked. Connections often uses tiny words to hide big categories. A two-letter answer can be slang, an abbreviation, a state code, a chemical symbol, or part of a phrase. BO happened to be the everyday smell one.

The simplest definition is this: BO means an unpleasant body smell, especially from sweat.

It does not mean sweat itself. Fresh sweat is often not the main problem. The smell usually comes when sweat mixes with bacteria on the skin or sits in clothing. But in casual English, people do not usually explain the science. They just say BO.

Examples in plain English:

“Someone in this elevator has serious BO.”

“I forgot deodorant after practice, and now I am worried about BO.”

“This shirt still has BO even after I washed it.”

“The locker room smelled like BO and old sneakers.”

“My gym bag is basically a BO museum.”

The tone matters. BO is not a fancy medical phrase. It is casual and direct. You might say “body odor” in a health article, school notice, product label, or polite conversation. You might say “BO” when talking with friends or joking about a smell.

That does not mean BO is always rude. It depends on how you use it. Saying “I have BO after that run” is normal self-deprecating humor. Saying “You have BO” to someone can sound harsh, especially in public. It is one of those small phrases that can feel bigger when aimed at a person.

A softer way to say it is: “You may want to freshen up,” “Do you need deodorant?” or “I think your shirt picked up a smell.” Those are still awkward sentences, because smell conversations are awkward by nature, but they land better than announcing BO like a referee.

In word games, BO is useful because it is short and slippery. It can look like a name. Bo can be a person’s name, as in Bo Jackson or Bo Burnham. It can also be part of brand names, place names, or initials. But when written as BO in all caps, body odor is one of the most common meanings.

That is exactly why it fit the Connections grid. AMMONIA had a chemical smell. DURIAN had a famous fruit smell. WET DOG had a pet smell. BO had the human smell. The group was not “gross things,” though a solver might joke that it was. It was more precise: sources of distinctive smells.

If DURIAN was the word that slowed you down, the same-day explainer at durian meaning guide covers why durian is famous for its smell and why it appears in trivia. If DRAWING looked odd in the mansion-room group, drawing room meaning guide explains why a drawing room is not mainly about sketching.

Common mistake: thinking BO means “bad odor.”

That guess makes sense because BO often is a bad odor. But the actual phrase is body odor. “Bad odor” is too broad. A trash can, wet dog, durian, and ammonia can all be bad odors, but they are not BO. BO points to a body smell specifically.

Another mistake is treating BO as always disgusting or insulting. In casual use, it is often just practical. Someone might say, “This deodorant helps with BO,” and that is not an insult. It is just product language. But when used about a person, it can feel personal fast.

Another wrong path in puzzles is reading BO as “B.O.” and looking for initials. That can happen, but context decides. If the surrounding words are smells, hygiene, sweat, deodorant, or locker rooms, body odor is the safest reading.

Related terms and phrases:

Body odor: the full phrase behind BO.

Deodorant: a product used to reduce or cover underarm smell.

Antiperspirant: a product that reduces sweating, often confused with deodorant.

Sweat: liquid from the skin; related to BO but not identical.

Musk: a strong smell, sometimes used for natural body scent or perfume notes.

Stink: a blunt word for a bad smell.

Odor: a neutral or formal word for smell.

Funk: casual slang for a strong or stale smell. “This room has a funk” means the room smells off.

Reek: to smell very strongly and badly. “His shoes reek” is stronger than “His shoes smell.”

BO also has a funny place in English because it is short enough to sound almost cute, but the thing it names is not cute at all. That contrast is why it works in jokes. “I brought snacks, water, and emergency deodorant because I respect the group chat” is not technically a BO sentence, but BO is the invisible punchline.

In the May 29 Connections puzzle, BO was a good reminder to sort by function. The word did not look like AMMONIA, DURIAN, or WET DOG. But all four could answer the question, “What has a strong, recognizable smell?” That is the kind of thinking Connections rewards.

The daily hub at the daily Connections guide explains the full grid, including how the smell group crossed paths with the mansion-room and PA groups. For the next puzzle in sequence, use the daily Connections guide.

A quick usage guide:

Use BO when the context is casual.

Use body odor when the context is formal, medical, workplace-related, or polite.

Avoid using BO as a public label for another person unless you are trying to be rude. Smell is personal, and people remember those comments.

In a puzzle, ask what kind of abbreviation it is. BO can be a name, initials, or body odor. The surrounding words tell you which one is doing the work.

So the short answer is simple: BO means body odor. In the Connections puzzle, it was one of four sources of distinctive smells, sitting beside ammonia, durian, and wet dog. Small clue, big smell.