Volunteer: a person who freely offers to take part in an enterprise or undertake a task. / K0 }8 b+ r) ?1 [synonyms: subject, participant, case, patient; informalguinea pig6 N4 h& y" X9 x7 w3 u2 ^, f4 E
"each volunteer was tested three times" 7 {, O! j) u* ~/ U c