ἄρθρον (arthron)

a joint , (Sophocles Tragicus): especially the socket of the ankle-joint , (Herdotus Historicus):—;in plural joined with some other word, ἄρθρα ποδοῖν the ankles, (Herdotus Historicus); ἄρθρων ἤλυσις the legs, (Euripides); ἄρθρα τῶν κύκλων the eyes, (Sophocles Tragicus); ἄρθρα στόματος the mouth, (Euripides) (ML)