疑惑
ぎわく · giwaku · JLPT N1 · noun
doubt
疑 = doubt + 惑 = confusion: 疑惑 stacks doubt on top of puzzlement
Both characters carry a sense of uncertainty, so the compound intensifies it into misgivings or suspicion. The same 惑 appears in 迷惑 (to bewilder or mislead).