suspect
/səˈspekt/·서스펙트·verb, noun
to believe something to be likely true; a person under suspicion
LatinCEFR B1
Root
sus- (from under) + Latin 'spectare' (to look)
Latin suspectus (looked at from below, mistrusted) → Old French suspect → English suspect
In a word
sus- (from under) + spect (look) = 'look from below, sideways'. Not a head-on gaze — an angled, glancing look. That angle is what makes it suspicion. A detective "checking" a suspect is, literally, looking at them from under. Honest looks travel level; suspicious looks tilt.
Examples
Police questioned the main suspect.
I suspect she already knows the answer.
His behaviour started to look suspicious.
Related
inspectrespectsuspicionsuspiciousaspect