Crooked is an adjective. When something is said to be crooked, it is bent, twisted or not in a straight line. Thus a deformed object is crooked. For example: the picture is crooked- move it a little to the left. In this it is conveyed that the picture was not properly hung. Another example: crooked teeth. This says that the teeth are not in a straight line. Figuratively, crooked could also mean dishonest. For example: a crooked policeman. This indicates that the policeman did not possess a loyal character and was not honest.
When someone does something deceitfully, he is said to be doing it crookedly. Thus crooked is used in its adverb form, crookedly. Words synonymous to crooked would be angled, askew, awry, bendy, bent, bowed, contorted, curved, curving, deformed, gnarled, lopsided, misshapen, off-centred, tortuous, twisted, twisty, warped, winding and zigzag. Criminal, corrupt, culpable, nefarious, knave and felonious are some other synonyms that could be used for crooked.
When someone does something deceitfully, he is said to be doing it crookedly. Thus crooked is used in its adverb form, crookedly. Words synonymous to crooked would be angled, askew, awry, bendy, bent, bowed, contorted, curved, curving, deformed, gnarled, lopsided, misshapen, off-centred, tortuous, twisted, twisty, warped, winding and zigzag. Criminal, corrupt, culpable, nefarious, knave and felonious are some other synonyms that could be used for crooked.