IPA: //ʌnˌsɛlfˈkɒnʃəs//
KK: /ʌnˌsɛlfˈkɒnʃəs/
Not feeling awkward or embarrassed about oneself; behaving in a natural and genuine way without being overly aware of how one is perceived by others.
She danced with an unselfconscious joy that made everyone smile.
Unselfconscious → It is formed from "un-" (meaning not), "self" (meaning one's own person), and "conscious" (from Latin "conscire", meaning to be aware). The word describes a state of not being aware of oneself or one's actions, often implying a naturalness or lack of self-awareness.
Think of 'not' ('un-') being aware of 'oneself' ('self') — that's why unselfconscious means not being aware of oneself.