Genitive Form: Ghleann Rathais

Sources

Ràthais: Diack, Place-Names of Pictland, i, 113
ra-ash [comment by Alexander: rathais]: Diack, Inscriptions, 196
Rathais: Watson notebooks, CW12
Rathais: Watson in Dwelly

See here for more details. The name and settlement are modern, dating from 1948. It is named from the earls of Rothes who owned some of the land upon which Glenrothes was built. Glen was added but denotes nothing topographically.
The early forms above are for Rothes in Moray, from whom the earls of Rothes are named.

Additional Information

Glenrothes Fire Station ~ Stèisean-Smàlaidh Ghleann Rathais

Glenrothes with Thornton ~ Gleann Rathais le Thornton