Sesquitertial: occupying a fourth part.
Sessile: closely seated: the abdomen, when it is closely attached for nearly or quite its full width to the thorax.
Sessiliventres: Hymenoptera in which the abdomen is sessile.
Seta -ae: a pointed bristle or long stiff hair: slender, hair-like appendages.
Setaceous: bristle-shaped: slender, gradually tapering to a tip.
Setarious aristate: the dipterous antenna when the arista is simple.
Setiferous: = setigercus; q.v.
Setiform: in the form of a bristle or seta: when a slender short bristle arises from a thicker basal joint.
Setigenous: the hypodermal cells that give rise to setae.
Setigerous: bearing setae or bristles; e.g. punctures.