a mature, female reproductive cell or egg, typically larger than a sperm cell, capable of fusing with a sperm cell during fertilization to form a zygote
例
Human females typically release one ovum during each menstrual cycle.
人間の女性は通常、月経周期ごとに1つの卵子を放出します。
Fertilization occurs when a sperm cell penetrates the protective layers of the ovum.