1
general::
Date more than one person; avoid an exclusive commitment. For example, All of Joe's friends are married now, but he continues to play the field. This term originated in British horseracing, where it meant "to bet on every horse in a race except the favorite." It was transferred to other activities about 1930.
American Heritage Idioms
2
general::
Phrase(s): play the field
to date many different people rather than just one. • When Tom told Ann good-bye, he said he wanted to play the field. • He said he wanted to play the field while he was still young.
McGrawhill's American Idioms And Phrasal Verbs