Roget's Thesaurus

#519. Unintelligibility

Nouns

unintelligibility; incomprehensibility, imperspicuity; inconceivableness, vagueness etc. adj.; obscurity; ambiguity etc. 520; doubtful meaning; uncertainty etc. 475; perplexity etc. (confusion) 59; spinosity; obscurum per obscurius [Lat.]; mystification etc. (concealment) 528; latency etc. 526; transcendentalism. paradox, oxymoron; riddle, enigma, puzzle etc. (secret) 533; diagnus vindice nodus [Lat.]; sealed book; steganography, freemasonry. pons asinorum [Lat.], asses' bridge; high Dutch, Greek, Hebrew; jargon etc. (unmeaning) 517.

Verbs

be unintelligible etc. adj.; require explanation etc. 522; have a doubtful meaning, pass comprehension. render unintelligible etc. adj.; conceal etc. 528; darken etc. 421; confuse etc. (derange) 61; perplex etc. (bewilder) 475. not understand etc. 518; lose, lose the clue; miss; not know what to make of, be able to make nothing of, give it up; not be able to account for, not be able to make either head or tail of; be at sea etc. (uncertain) 475; wonder etc. 870; see through a glass darkly etc. (ignorance) 491. not understand one another; play at cross purposes etc. (misinterpret) 523.

Adjectives

unintelligible, unaccountable, undecipherable, undiscoverable, unknowable, unfathomable; incognizable, inexplicable, inscrutable; inapprehensible, incomprehensible; insolvable, insoluble; impenetrable. illegible, as Greek to one, unexplained, paradoxical; enigmatic, enigmatical, puzzling (secret) 533; indecipherable. obscure, dark, muddy, clear as mud, seen through a mist, dim, nebulous, shrouded in mystery; opaque, dense; undiscernible etc. (invisible) 447; misty etc. (opaque) 426; hidden etc. 528; latent etc. 526. indefinite, garbled etc. (indistinct) 447; perplexed etc. (confused) 59; undetermined, vague, loose, ambiguous; mysterious; mystic, mystical; acroamatic, acroamatical; metempirical; transcendental; occult, recondite, abstruse, crabbed. inconceivable, inconceptible; searchless; above comprehension, beyond comprehension, past comprehension; beyond one's depth; unconceived. inexpressible, undefinable, incommunicable. unpredictable, unforeseeable.

Phrases

it's Greek to me.