Estrogen or oestrogen?
estrogen is a noun meaning “Any of a group of steroids that are secreted by the ovaries and function as…”; oestrogen is a noun meaning “Alternative spelling of estrogen”. Wiktionary gives them as spellings of the same word. In written English (wordfreq, 2021 data) estrogen is about 9.1 times as common as oestrogen.
What is the difference between estrogen and oestrogen?
| estrogen | oestrogen | |
|---|---|---|
| Part of speech | noun | noun |
| Meaning | Any of a group of steroids that are secreted by the ovaries and function as female sex hormones | CommonwealthAlternative spelling of estrogen |
| Example | none recorded | none recorded |
| Forms | estrogens | oestrogens |
| Pronunciation | /ˈɛstɹəd͡ʒən/ /ˈiːstɹəd͡ʒən/ | not recorded |
| In writing | 2.3 times per million words | about once in every 4 million words |
Sources: estrogen and oestrogen in the English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0); written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).
Every current meaning of estrogen and oestrogen
estrogen
- 1
Any of a group of steroids that are secreted by the ovaries and function as female sex hormones
oestrogen
- 1
CommonwealthAlternative spelling of estrogen
Source: the English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0); obsolete, archaic, dialect and rare senses left out.
Which is more common, estrogen or oestrogen?
estrogen appears 2.3 times per million words; oestrogen about once in every 4 million words.
estrogen 2.3 times per million wordsoestrogen about once in every 4 million words
Source: written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).
How many people search estrogen vs oestrogen?
“estrogen vs oestrogen” is searched about 140 times a month on Google and 10 on Bing in the United States. Google counts close variants of a query together (“oestrogen vs estrogen”, “estrogen or oestrogen”).
Sources: Google Ads keyword data through DataForSEO and Microsoft Advertising keyword data through DataForSEO, the average month from September 2025 to August 2026.