IPA: //ʌnˈsɛlfɪʃnəs//
KK: /ʌnˈsɛlfɪʃnəs/
The quality of being willing to put others' needs before your own and not being selfish.
Her unselfishness was evident when she volunteered to help the less fortunate.
Unselfishness → It is formed from "un-" (meaning not) and "selfish" (from Old English "selfisc", meaning concerned with oneself) and the suffix "-ness" (meaning the state of being). The word "unselfishness" means the state of not being concerned with oneself, or selflessness.
Think of 'not' ('un-') being added to 'selfish' to remember that 'unselfishness' means being selfless or not focused on oneself.