IPA: //ʌnˈlʌvliər//
KK: /ʌnˈlʌvliər/
Not as attractive or pleasant as something else; less lovely.
The weather today is unlovelier than it was yesterday.
Unlovelier → It is formed from "un-" (meaning not) and "lovely" (from Old English "luflic", meaning full of love or pleasing). The suffix "-er" indicates a comparative form. Thus, "unlovelier" means not as pleasing or less full of love compared to something else.
Think of 'not' ('un-') being added to 'lovely' to remember that 'unlovelier' means less pleasing or less full of love.