IPA: /ˌʌn.rɪˈzɜːr.vɪd.li/
KK: /ʌnˈrɛzərvdli/
In a way that shows no hesitation or limits; completely and openly.
She accepted the invitation unreservedly, excited to join the celebration.
Unreservedly → It is formed from "un-" (meaning not) and "reserved" (from Latin "reservare", meaning to keep back or hold). The suffix "-ly" (meaning in a manner) indicates the manner of the action. Thus, "unreservedly" means in a manner that is not held back or constrained.
Think of doing something 'not held back' ('un-') and 'in a manner' ('-ly') that shows openness and freedom.