the fleshy part of the human body that you sit on
"he deserves a good kick in the butt"
"are you going to sit on your fanny and do nothing?"
a pompous fool
"The board fired him for being such an ass who thought his outdated ideas were still revolutionary."
hardy and sure-footed animal smaller and with longer ears than the horse
"The cowboy guided his ass over the rocky terrain, appreciating its sturdy legs and long ears that swiveled at every sound."
slang for sexual intercourse
"The movie was so graphic that I had to turn it off after they showed how much they enjoyed having sex in the shower."
Any of several species of horse-like animals, especially Equus asinus, the domesticated of which are used as beasts of burden.
"The researchers confirmed that the new genetic mutation affected the ASS enzyme, which is crucial for urea cycle metabolism."
Buttocks.
Initialism of argininosuccinate synthase.
In plain English: An ass is a stubborn donkey known for being slow and difficult to handle.
"The dog wagged its tail happily when he touched its ass with a gentle pat."
Usage: Do not use this word in formal or polite conversation; it is an offensive slang term for a human's buttocks that should be avoided in professional settings. The biological initialism you mentioned belongs entirely to scientific contexts and has no place in everyday speech.
Used after an adjective to indicate extremes or excessiveness.
"The heat was so ass that I couldn't stay outside for more than a minute."
In plain English: To say something is ass means to describe it as extremely bad or terrible.
"The car was going too fast, so I leaned back and let my ass ride until the next stoplight."
Usage: Do not use "ass" as an adverb; it is a vulgar noun that should never modify an adjective. Instead, use intensifiers like "really," "incredibly," or "extremely" to convey the sense of extreme excessiveness you intend.
The word "ass" entered English from Old English and ultimately traces back to Latin asinus, replacing an earlier native term. Its meaning expanded over time to describe a stupid person, reflecting the animal's ancient reputation for stubbornness.