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