STER
-ster. Etym: [OE. & AS. -estre, -istre.]
Definition: A suffix denoting the agent (originally a woman), especially a
person who does something with skill or as an occupation; as in
spinster (originally, a woman who spins), songster, baxter (=
bakester), youngster.
Note: Brewing, baking, and weaving were formerly feminine labors, and
consequently brewster, baxter, and webster meant, originally, the
woman (not the man) who brews, bakes, or weaves. When men began to
perform these duties the feminine appellations were retained.
Source: Webster’s Unabridged Dictionary 1913 Edition