στοιχεῖον
Alt. στοιχεῖον, ου, τό,
Etym. στοῖχος
properly, "one of a row": hence,
I. in the sun-dial, "the shadow of the gnomon", Ar.
II. generally, "one of a series, an elementary sound" of the voice, "a letter", Plat.:— κατὰ στοιχεῖον "in the order of the letters, alphabetically", Anth.
2. in pl. "the elements", Plat., etc.
3. "the elements of knowledge, rudiments", ἀρξάμενοι ἀπὸ τῶν στ. Xen.