lacking or not based on moral scruples or principles

an unprincipled person; unprincipled behavior.

not instructed in the principles of something (usually fol. by in ).

adjective

ethical , moral , principled

adjective

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-at-nothing , tricky , two-faced * , two-timing , unconscionable , underhand , unethical , unprofessional , unscrupulous , venal , wanton , ruthless , corrupt