Late Middle English; earliest use found in John Trevisa (c1342–?1402), translator. From classical Latin alectoria precious stone said to be found in the gizzards of cocks (Pliny) from Hellenistic Greek ἀλεκτορεία, use as noun (short for ἀλεκτορεὶα λίθος alectory stone) of feminine of ἀλεκτόρειος of a fowl from ancient Greek ἀλέκτωρ cock, lit. ‘defender’ + -ειος, suffix forming adjectives; compare -y.