The Old Welsh breenhin is the root of the name, meaning prince or king.

[3] This Old Irish personal name (pronounced [br'ēn-in']) is derived from a borrowing of the Old Welsh word breenhín, meaning 'a prince'.

[1] There is no etymological link with the feminine given name Brenda, which is thought to be derived from the Old Norse element brand, meaning '(flaming) sword'.

In some cases, the masculine given name Brennan may be used as a contracted form of Brendan, although it is etymologically unrelated.

It is derived from the surname Brennan, an Anglicised form of the Irish Ó Braonáin.