ἀριστερός
1. "left, on the left", Lat. sinister, ἐπ᾽ ἀριστερά towards, i. e. on, "the left", Il.; ἐπ᾽ ἀριστερὰ χειρός on the "left" hand, Od.; ἐξ ἀριστερῆς χειρός on "the left hand", Hdt.; or simply, ἐξ ἀριστερᾶς Soph.; ἐς ἀριστερήν, ἐν ἀριστερῆι Hdt.
2. metaph. "boding ill, ominous", because to a Greek augur, looking northward, the unlucky signs came from the left, Od.
Etym. Deriv. uncertain.