Meaning

noun an inscrutable person who keeps his thoughts and intentions secret

noun (Greek mythology) a riddling winged monster with a woman's head and breast on a lion's body; daughter of Typhon

noun one of a number of large stone statues with the body of a lion and the head of a man that were built by the ancient Egyptians

originFrom Sphinx, from Middle English Spynx, from Latin Sphinx, from Ancient Greek Σφίγξ (Sphínx), perhaps either from σφίγγω (sphíngō, “to squeeze, to strangle”) (whence also sphincter), of Pre-Greek origin, or from Egyptian Szp:p-A53-anx-n:x (šzp-ꜥnḫ, “divine image”, literally “living image”).

Etymology from Wiktionary, CC BY-SA 3.0