IPA: //ʌnˈskruːpjələs//
KK: /ʌnˈskrupjələs/
Lacking moral principles or ethics; willing to do anything to achieve a goal, regardless of what is right or wrong.
The unscrupulous businessman cheated his clients to make more money.
Unscrupulous → It is formed from the prefix "un-" (meaning not) and the root "scrupulus" (from Latin, meaning a small stone or a moral doubt). The word describes someone who is not troubled by moral doubts or scruples, hence lacking principles or ethics.
Think of someone who is 'not' ('un-') worried about 'moral doubts' ('scrupulus') — that's why unscrupulous means lacking in ethics.