Cadyn is a name of Irish origin and it means "from the combat". It is derived from the Irish surname Ó Cadhla, which was originally Ó Cadail, meaning "descendant of Cadail", with Cadail being a personal name that means "combat". The name has been used as both a first name and a surname throughout history.
"Cadyn's popularity peaks around the mid-2000s with a high of 35 births in 2005 and again at 48 in 2008, but it has been steadily declining since then."