formerly also teaze, Old English tæsan "pluck, pull, tear; pull apart, comb" (fibers of wool, flax, etc.), from Proto-Germanic *taisijan (source also of Danish tæse, Middle Dutch tesen, Dutch tezen "to draw, pull, scratch," Old High German zeisan "to tease, pick wool").
The original sense is of running thorns through wool or flax to separate, shred, or card the fibers. The figurative sense of "vex, worry, annoy" (sometimes done in good humor) emerged 1610s. For similar sense development, compare heckle. Hairdressing sense is recorded from 1957. Related: Teased; teasing; teasingly.