Dictionary.net

• the time in the menstrual cycle when fertilization is most likely to be possible (7 days before to 7 days after ovulation)

2006 - WordNet 3.0
By Princeton University

• the time in the menstrual cycle when fertilization is most likely to be possible (7 days before to 7 days after ovulation)

2011 - English Dictionary Database
By DataStellar Co., Ltd