i Register
In some senses, sinful is marked as colloquial. Watch for register when choosing this word.
ADJ.
decadent, immoral, most, rich
VERB + SINFUL
am, cheating, hands, interest, met, outraged, rate, resist
SINFUL + NOUN
cookies, girl, gluttony, god, man, nature, person, perversion
PREP.
in
ADV.
inherently, sincerely, utterly