complex, complicated, crabbed, cramp, difficult, garbled, hard, hard to understand, impracticable, impractical, inoperable, insuperable, insurmountable, intricate, jumbled, knotty, obfuscated, obscure, obscured, overtechnical, perplexed, scrambled, too much for, tough, unachievable, unattainable, uncompassable, undoable, uneffectible, unnegotiable, unperformable, unrealizable, unsurmountable, unworkable