This is the 4647th most frequent Russian word.
добровольцем
"Volunteer."
The word 'добровольцем' refers to someone volunteering in this context.
Он оставался добровольцем до конца проекта.
He remained a volunteer until the end of the project.
The word 'добровольцем' emphasizes the voluntary choice to participate.
Она решила стать добровольцем, чтобы помочь благотворительной организации.
She decided to become a volunteer to assist the charitable organization.
Here, 'добровольцем' denotes the state or role of volunteering, highlighting the action's benefits.