Declan is an Irish Gaelic name that means "man of the river" or "fruitful". It was traditionally used by the O'Dubhthaigh clan, who were chieftains of the county of Claire. In modern times, Declan has gained popularity worldwide and is often used as a given name for boys.
The name Declen experienced fluctuations in popularity over the years with a notable increase from 6 births in 2014 to 11 in 2015 and then another rise from 8 in 2020 to 10 in 2022.