Lacking integrity is a term used to describe someone who is not honest or trustworthy. UNPRINCIPLED (12 letters) is a synonym for this, meaning someone who does not adhere to moral principles. CORRUPT (7 letters) is another word for this, referring to someone who has been bribed or influenced by money or power. Lastly, LOOSE (5 letters) is a term used to describe someone who is not bound by any rules or regulations. All of these words can be used to describe someone who is lacking in integrity.