sketchy adj.

1660s, scetch, "rough drawing intended to serve as the basis for a finished picture," from Dutch schets or Low German skizze, both apparently being 17c. artists' borrowings from Italian schizzo "sketch, drawing."

This is commonly said to be from Latin *schedius (OED compares schedia "raft," schedium "an extemporaneous poem"), which is from or related to Greek skhedios "temporary, extemporaneous, done or made off-hand," related to skhema "form, shape, appearance" (see scheme (n.)). But according to Barnhart Italian schizzo is a special use of schizzo "a splash, squirt," from schizzare "to splash or squirt," a word of uncertain origin. German Skizze, French esquisse, Spanish esquicio are said to be likewise from Italian schizzo.

The extended sense of "brief account" is from 1660s. The meaning "short and slightly constructed play or performance, usually comic" is from 1789; in music, "short composition of a single movement," 1840. Sketch-book "book with blank leaves of drawing paper" is recorded from 1820; it also was used of printed books composed of literary sketches.

In old slang, a hot sketch (simple sketch for short) was "amusing, ridiculous person" (1909). It turns up first in descriptions of stage entertainment, and a theatrical help-wanted ad from 1906 seeks "a good hot sketch team" for "all circus and vaudeville lines."

Miss Cora Martini, the Cuban dancer, might be termed a hot sketch. When Girard announced her, the crowd asked her age. Girard said he didn't know as he never liked to ask ladies personal questions. The house told him it was just as well, seeing she wouldn't tell him anyhow. ["Amateur Night at the Gotham," Brooklyn Weekly Chat, Nov. 30, 1907]

adjective suffix, "full of or characterized by," from Old English -ig, from Proto-Germanic *-iga- (source also of Dutch, Danish, German -ig, Gothic -egs), from PIE -(i)ko-, adjectival suffix, cognate with elements in Greek -ikos, Latin -icus (see -ic). Originally added to nouns in Old English; used from 13c. with verbs, and by 15c. even with other adjectives (for example crispy). Adjectives such as hugy, vasty are artificial words that exist for the sake of poetical metrics.