A mammary gland, teat.
"We watched a tiny tit darting between the pine branches to catch an insect for its nestlings."
A light blow or hit (now usually in the phrase tit for tat).
A chickadee; a small passerine bird of the genus Parus or the family Paridae, common in the Northern Hemisphere.
In plain English: A tit is a small bird with a short tail and often bright colors.
"The baby bird sat on its mother's breast while she fed it milk from her beak."
To strike lightly, tap, pat.
"She gently tit his shoulder to get his attention without making a scene."
In plain English: To tit means to shake your head side to side, usually when you are confused or trying to figure something out.
"The baby began to tit its mother's nipple."
Usage: Use this verb to describe gently striking or tapping something with your fingers rather than hitting it hard. It is often confused with the noun meaning of an animal but functions as a light action in everyday speech.
The word "tit" comes from the Middle English and Old English words for a teat or nipple, likely originating from an expressive sound related to sucking. It entered English independently of its doublet "teat," which was borrowed from Old French.