safe period

WordReference Random House Unabridged Dictionary of American English © 2026

safe′ pe′riod, 

1. Physiology an interval of the menstrual cycle when fertilization is considered to be least likely, usually a number of days prior and subsequent to the onset of menstruation.

• 1915–20

Collins Concise English Dictionary © HarperCollins Publishers::

safe period noun

1. the period during the menstrual cycle when conception is considered least likely to occur
   See also rhythm method