Volunteer: a person who freely offers to take part in an enterprise or undertake a task. ; s: x" H* [9 ]1 b. K/ @synonyms: subject, participant, case, patient; informalguinea pig. F7 Y& [, v5 {' V$ `0 o
"each volunteer was tested three times" 8 n8 P- j* }& | t. d7 I' B