unprincipled

Synonyms: abandoned amoral bent cheating conscienceless crooked deceitful devious dirty-dealing dishonest dissolute double-crossing double-dealing immoral licentious mercentary praetorian profligate reprobate shady sly stop-atnothing tricky two-faced two-timing unconscionable underhand unethical unprofessional unscrupulous venal wanton

Antonyms: ethical moral principled