IPA: /ʌnˈlaɪkliər/
KK: /ʌnˈlaɪkliər/
Less likely to happen or be true than something else.
It seems unlikelier that they will win the game this time.
Unlikelier → It is formed from "un-" (meaning not) and "likely" (from Old English "liclic", meaning having the quality of). The word "unlikelier" means not having the quality of being likely, or less probable than something else.
Think of 'not' ('un-') combined with 'having the quality of' ('likely') to remember that 'unlikelier' means something is less probable.
No commonly confused words.