不審
ふしん · fushin · JLPT N1 · noun
suspicious
🔍 不 (not) + 審 (examine, judge) = not yet examined, so suspicious
審 is the character for a court hearing or trial. 不審 means a matter has not been heard or cleared, so it looks suspicious, and by extension it can mean doubt or infidelity.
不 — single pictograph; bird flying upward
Originally a pictograph in oracle bone script, traditionally interpreted as a bird flying up toward the sky and unable to come down, suggesting negation or refusal. Over time it became the standard negation word in Chinese, used before verbs and adjectives to mean 'not'.