SIMILE—comparison, similitude.
SIMPLE—single, uncompounded, artless, plain. (Complex, compound.)
SIMULATE—dissimulate, dissemble, pretend.
SINCERE—candid, hearty, honest, pure, genuine, real. (Insincere.)
SITUATION—condition, plight, predicament, state.
SIZE—bulk, greatness, magnitude, dimension.
SLAVERY—servitude, enthrallment, thralldom. (Freedom.)
SLEEP—doze, drowse, nap, slumber.
SLEEPY—somnolent. (Wakeful.)
SLOW—dilatory, tardy. (Fast.)