IPA: //ʌnˈkæʧi//
KK: /ʌnˈkæʧi/
Not able to attract attention or interest; lacking appeal or memorability.
The song was so uncatchy that no one could remember the tune.
Uncatchy → It is formed from "un-" (meaning not) and "catchy" (from the verb "catch" meaning to capture or seize, combined with the suffix "-y" which indicates a quality). The word "uncatchy" means not having the quality of being able to capture attention or interest.
Think of 'not' ('un-') being added to 'catchy' — so if something is 'uncatchy', it simply does not grab your attention.