おなら

おなら is the standard casual word for flatulence. The お prefix (from the honorific お) softens the word, making it more acceptable than cruder alternatives.

Common expressions

• おならをする: to fart (volitional nuance)
• おならが出(で)る: to pass gas (involuntary nuance)
• おならを我慢(がまん)する: to hold in a fart
• おならが臭(くさ)い: the fart smells

Register

Casual but not vulgar. Acceptable among friends and family, and commonly used by and around children. Would be avoided in formal or polite company.

Similar words

• 屁(へ): cruder, more blunt (also used in idioms like 屁(へ)でもない, meaning "it's nothing")
• 放屁(ほうひ): medical/formal term (rarely heard in daily life)