1
general::
Alternate, as in Since there is only one horse, Beth and Amanda are taking turns riding. This phrase uses turn in the sense of "one of a series of actions done in succession." [Late 1300s] Also see IN TURN.
American Heritage Idioms
2
general::
Phrase(s): take turns ((at) doing something) [and] take turns (at something); take turns (with something)
[for two or more people] to alternate in doing something. • Let’s take turns with mowing the lawn. • Do you want to take turns at answering the telephone?, Phrase(s): take turns (with something)
Go to take turns ((at) doing something).
McGrawhill's American Idioms And Phrasal Verbs