* Elwy can be a male given name, derived from the Welsh word "elw" meaning "profit" or "gain".
* Elwy is also the name of a river in North Wales, which flows into the Dee estuary. This river name is likely related to the meaning of "profit" or "gain", referring to its importance for fishing and trade.
* Elwy can also be a surname.
Without more context, it's impossible to know exactly what "Elwy" means in English.