oestrogen vs estrogen

oestrogen and estrogen both are nouns.

Word	Noun	Adjective	Verb	Adverb
oestrogen	Yes	No	No	No
estrogen	Yes	No	No	No

As nouns, oestrogen and estrogen are synonyms defined as:

oestrogen and estrogen: a general term for female steroid sex hormones that are secreted by the ovary and responsible for typical female sexual characteristics

oestrogen (noun)	estrogen (noun)
a general term for female steroid sex hormones that are secreted by the ovary and responsible for typical female sexual characteristics	a general term for female steroid sex hormones that are secreted by the ovary and responsible for typical female sexual characteristics