unprincipled

/ˈʌnˌprɪnsəpəld/

An unprincipled person follows no moral code, has no integrity, and should not be trusted, like the guy who offers to help an old lady across the street but steals her purse instead.

No, unprincipled isn't a word we use to describe a school that's missing its principal — we're talking about the -ple word here. If you don't have principles, which is what unprincipled really means, then you don't have scruples or morals. You're likely to do just about anything bad, like break rules, take advantage of people, tell lots of lies, and extort people's lunch money.

Definitions of unprincipled

1. adjective

   lacking principles or moral scruples
   “"freedom from coarse unprincipled calumny"- A.E.Stevenson”

   synonyms: amoral

   unscrupulous

   without scruples or principles

   antonyms:

   principled

   based on or manifesting objectively defined standards of rightness or morality

   high-principled

   having high principles

   scrupulous

   having scruples; arising from a sense of right and wrong; principled
2. adjective

   having little or no integrity
   synonyms:

   dishonorable, dishonourable

   lacking honor or integrity; deserving dishonor