abstruse (adj.) Look up abstruse at Dictionary.com
1590s, "remote from comprehension," from Middle French abstrus (16c.) or directly from Latin abstrusus "hidden, concealed, secret," past participle of abstrudere "conceal, hide," literally "to thrust away," from ab- "away" (see ab-) + trudere "to thrust, push," from PIE root *treud- "to press, push, squeeze" (see threat). Related: Abstrusely; abstruseness.