on a hunch (adjective) conjectural: speculative
Sinonime: aloof, antisocial, brooding, clammed up, close, close-mouthed, cold, curt, distant, dour, dried-up, dumb, incommunicative, laconic, mum, mute, quiet, reserved, reticent, sententious, silent, sparing, speechless, tight-lipped, tightlipped, uncommunicable, uncommunicative, unexpressive, unforthcoming, withdrawn
Antonime: certain,
factual, proven,
real,
truthful