1540s, a word used for any small animal or object (as in compound forms such as

titmouse

tomtit

, etc.); also used of small horses. Similar words in related senses are found in Scandinavian (Icelandic

tittr

, Norwegian

tita

"a little bird"), but the connection and origin are obscure; perhaps, as OED suggests, the word is merely suggestive of something small. Used figuratively of persons after 1734, but earlier for "a girl or young woman" (1590s), often in deprecatory sense of "a hussy, minx."