sĕr-o (sert-), I join, compose: series, assert, desert, exert, insert, concert.
servo (servāt-), I save: con-serve, conservator, preservation, conservatory.
servus, a slave; serv-īre, to serve: servile, servant, sergeant, serf, service.
signum, mark, sign; sign-o (signāt-), I mark, seal: signal, signet, signature, signatory, significant, assign-ment, re-signation (a signing back).
similis, like; simul, together; simul-o (simulāt-), I pretend: similar and similitude (Fr.), as-similate, simul-taneous, simulate, assembly (Fr.).
sōl, sun: solar, sol-stice (= sol-stit-ium; stare) (Fr.), para-sol (par-, ward off).
sŏlidus (and soldus), firm; also a gold coin (military pay): solidify and solder (Fr.), solidarity (Fr.), consolidate, con-sols, soldier (Fr.).
sōlus, alone: through Fr., sole, solitude, solitary, solitaire, de-solate, solo.
solv-o (sŏlūt-), I loose, pay: solvent, ab-solve, soluble (Fr.), dis-solute.
somnus, sopor, sleep: in-somnia, somnolence, somn-ambulist, sopori-fic.