menstrual cycle vs fertile period

menstrual cycle and fertile period both are nouns.

Word	Noun	Adjective	Verb	Adverb
menstrual cycle	Yes	No	No	No
fertile period	Yes	No	No	No

menstrual cycle (noun)	fertile period (noun)
a recurring cycle (beginning at menarche and ending at menopause) in which the endometrial lining of the uterus prepares for pregnancy; if pregnancy does not occur the lining is shed at menstruation	the time in the menstrual cycle when fertilization is most likely to be possible (7 days before to 7 days after ovulation)