The term "ovulum" typically refers to the female reproductive cell, or egg, of animals. Although there are not many synonyms for this specific word in English, there are several related terms that can be used in a similar context. For example, "oocyte" and "ovum" are commonly used to describe the unfertilized egg in mammals, while "gamete" or "germ cell" can refer more generally to either male or female reproductive cells. Additionally, terms such as "zygote," "embryo," and "fetus" may be used to describe the stages of development after the egg has been fertilized. Overall, while there may not be many direct synonyms for "ovulum," there are plenty of related terms that can be used in a similar context.