Abstruse

Definition: 1. Hard to understand; recondite; esoteric.
2. Obsolete; secret; hidden.

Pronunciation: ab-stroos

Origin/History: c. 1600, from L. abstrusus, pp. of abstrudere "conceal", lit. "to thrust away", from ab- "away" + trudere " thrust, push"

Used in sentence: "I find this situation most abstruse".