θυρεός

A. stone put against a door to keep it shut, Od. 9.240, 313.

II. oblong shield (shaped like a door), PSI 4.428.36 (iii B.C.), Inscr. ap. Plu. Pyrrh. 26, Callix. 2; hence, of the Roman scutum (opp. ἀσπίς,= clipeus), Plb. 2.30.3, 6.23.2, D.H. 4.16, cf.Ep.Eph. 6.16, Apollod. Poliorc. 163.2, Arr. Tact. 3.2, etc.

III. disk forming part of καθετήρ, IG 11(2).287 B 68 (Delos, iii B.C.).

IV. Math., oval, Procl. in Euc. 1 Deff. 3,8.