sinuosité, n.f., sinuosity, winding, meandering.
sinus (-nus), n.m., (math.) sine; (anat.) sinus.
siphilis, n.f. V. syphilis.
siphilitique, adj. V. syphilitique.
siphon, n.m., siphon; water-spout (at sea).
sire, n.m., sire (title of kings and emperors); ☉sir (lord); (in fables) squire. Un pauvre —; a poor wretch, wight.
sirène, n.f., siren, mermaid, sea-maid.
sirius (-us), n.m., (astron.) Sirius.
siroco or ☉siroc, n.m., Sirocco.
sirop, n.m., syrup.