IPA: /ʌnˈhæpɪnəs/
KK: /ʌnˈhæpɪnəs/
The state of feeling sad or not content.
Her unhappiness was evident when she didn't smile at the party.
Unhappiness → It is formed from "un-" (meaning not) and "happiness" (from Middle English "hap" meaning chance or fortune, combined with the suffix "-ness" meaning the state of). The word "unhappiness" means the state of not being happy or the absence of happiness.
Think of 'not' ('un-') combined with the 'state of being fortunate or happy' ('happiness') — that's why unhappiness means the state of not being happy.