itty adj.

Old English lytel "not large, not much, small in size or number; short in distance or time; unimportant,"

from Proto-Germanic *lutilla- (source also of Old Saxon luttil, Dutch luttel, Old High German luzzil, German lützel "little"), perhaps originally a diminutive of the root of Old English lyt "little, few," from PIE *leud- "small."

"Often synonymous with small, but capable of emotional implications which small is not" [OED]. Now with less, least, but formerly and in dialect littler, littlest. In terms of endearment from 1560s. Meaning "younger" (of a brother, sister, etc.) is from 1610s. As an adverb, Old English lytel.

Little while "a short time" is from 12c. Phrase the little woman "wife" attested from 1795. Little people "the faeries" is from 1726; as "children" it is attested from 1752; as "ordinary people" (opposed to the great) from 1827. Little death "orgasm" (1932) translates French petite mort. Little Neck clams (1884) are so called for Little Neck, a "neck" of land on Long Island's North Shore, where they first came into favor. Little green men "space aliens" is from 1950. Little boys' room (or girls') as a euphemism for "lavatory" is from 1957. Little breeches for "boy" is by 1785. Little black dress is from 1939.

At the beginning of summer, smart women who stay in town like to wear sheer "little black dresses." Because most "little black dresses" look alike, retailers struggle each year to find something which will make them seem new. [Life magazine, June 13, 1939]

"charmingly small," 1882, from itty (baby-talk form of little) and/or bitsy. Bitsy-itsy is recorded from 1875. Itty-bitty from 1849; tiddy-itty from 1852.

The fond old captain used to talk of her very much as if she were six months old, and fractions in teething, calling her his Peetums-keetums, his Pitsy-itsy-kitsy and such like, which annoyed the girl, .... ["M.B.," "John's Wife," in "Tales of the Day," 1861]