IPA: /ʌnˈpɒpjʊlə/
KK: /ʌnˈpɑpjələr/
Not liked or accepted by most people.
The movie was unpopular and did not do well at the box office.
Unpopular → It is formed from "un-" (meaning not) and "popular" (from Latin "popularis", meaning of the people). The word "unpopular" means not liked or favored by the people.
Think of 'not' ('un-') being added to 'popular', which means liked by many. This helps you remember that 'unpopular' refers to something that is not liked.