Brynn

The correct and only way to spell Bryn is with one N. Bryn is Welsh for hill, a language and a word that has existed for roughly 4000 years. Now, less than 300 years ago the nation of America was born and with it too the double n version of Bryn. I am partially annoyed by this as Americans constantly ask me "Isn’t that a girl's name? (I'm a Welsh boy) but also as it is symbolic of the suppression of the Welsh language by Westminster (UK’s government) in order to squash Welsh nationalism and its people. Cymru am byth.

Brynn has Welsh origins, as it derives from the word bryn, meaning hill.

"Bryn" and "Brynn" are both Welsh in origin and mean the same thing. One is almost certainly a variant of the other.