IPA: /ʌnˈɛθɪkəl/
KK: /ʌnˈɛθɪkəl/
Not morally right or acceptable; something that goes against moral principles.
It is unethical to lie in order to gain an advantage.
Unethical → It is formed from "un-" (meaning not) and "ethical" (from Greek "ethikos", meaning moral or relating to ethics). The word "unethical" means not conforming to accepted standards of morality or ethics.
Think of 'not' ('un-') being added to 'moral standards' ('ethical') — that's why unethical means not following moral standards.