形容词

1. 自愿的;志愿的;主动的;自发的
Voluntary actions or activities are done because someone chooses to do them and not because they have been forced to do them.

1. composition (often improvised) for a solo instrument (especially solo organ) and not a regular part of a religious service or musical performance

2. (military) a person who freely enlists for service

Synonym: volunteermilitary volunteer