Synonyms for Unethical:

adj.

dishonest, immoral (adjective)
unfair, wrong, unscrupulous, unprincipled, dishonorable.
unconscionable (adjective)
amoral.
unjust (adjective)
unfair.

n.

deviant, sordid, wrong, unfair, unprincipled, gross, dishonest, perverted, amoral. unethical (noun)
dishonourable, immoral, dishonorable, base.

Other synonyms:

unprincipled, conscienceless, deviant, perverted, sordid, amoral. unconscionable, dishonest. ruthless, gross. unprincipled
unscrupulous.
Other relevant words:
conscienceless, unfair, deviant, sordid, amoral, unscrupulous, gross, ruthless, wrong, unconscionable, perverted, unprincipled, dishonest.