Quinlan is of Irish origin, derived from the Gaelic 'Coinnleán', which means 'descendant of Connla'. This name was traditionally associated with a legendary hero in Irish mythology, Connla, who appears in the tale of 'The Exile of the Sons of Usnach'. The name Quinlan became quite popular during the 19th century among Irish immigrants settling in North America. It is often found as a surname but has also been used as a given name from time to time. There are no specific records of Quinlan being celebrated on any particular day, and its popularity seems to have waned since the mid-20th century.
"The name Quinlan experienced a notable peak in popularity around the late 1990s and early 2000s, with over 100 births per year from 1999 to 2003. However, it has since seen a significant decrease, dropping below 50 births per year starting from 2016."