fertilized ovum vs zygote

fertilized ovum and zygote both are nouns.

Word	Noun	Adjective	Verb	Adverb
fertilized ovum	Yes	No	No	No
zygote	Yes	No	No	No

As nouns, fertilized ovum and zygote are synonyms defined as:

fertilized ovum and zygote: (genetics) the diploid cell resulting from the union of a haploid spermatozoon and ovum (including the organism that develops from that cell)

fertilized ovum (noun)	zygote (noun)
(genetics) the diploid cell resulting from the union of a haploid spermatozoon and ovum (including the organism that develops from that cell)	(genetics) the diploid cell resulting from the union of a haploid spermatozoon and ovum (including the organism that develops from that cell)