Where does “Terrilynn” come from?

Terrilynn (English) comes from English Lynn, from Proto-Brythonic llɨnn, from Proto-Celtic lindom — liquid; lake.

Ancestry of “Terrilynn”, step by step

Terrilynn traces back through two separate lines of ancestry.

via English Lynn

StepLanguageWordMeaning
1EnglishLynnA local name for King's Lynn, Norfolk, England
2Proto-Brythonicllɨnnpool
3Proto-Celticlindomliquid; lake

via English Terri

StepLanguageWordMeaning
1EnglishTerriA female given name; a spelling variant of Terry, diminutive of Teresa
Every word from Proto-Celtic lindom →Every word from Proto-Brythonic llɨnn →Every word from English Lynn →