Teagan comes from the Irish surname Ó Tadhgáin, meaning "descendant of Tadhgán", a pet form of Tadhg, which translates as "poet" or "philosopher"; some sources also link it to the Welsh teg, "fair". It is used for both sexes in the United States but has been far more common for girls. Teagan rose from number 838 in 2000 to a peak of number 150 in 2016 and ranks number 341 in 2025.