volunteer

volunteer verb uk/ˌvɒlənˈtɪər/ us volunteer verb
(ARMY)

to join the army, navy, etc without being officially told to join

поступать добровольцем
In 1939 he volunteer ed for active service. volunteer verb
(NOT PAID)

B2 someone who does work without being paid, especially work that involves helping people

доброволец, волонтер
a Red Cross volunteer volunteer noun [C]