Fionn \fi(o)-nn\ as a boy's name is a variant of Finbar (Irish, Gaelic), Finian (Irish, Gaelic) and Finn (Irish, Gaelic, Old German), and the meaning of Fionn is "white or fair head; fair; from Finland".

The baby name Fionn sounds like Fin, Vonn and Winn. Other similar baby names are Fionan, Fonz, Fons, Conn, Dion, Deonn, Donn, Finan, Flann, Flynn, Flinn, Frann, Eion, Jonn, Lion, Lionni, Lioni, Linn, Lonn, Ronn, Rion, Shonn, Sion and Zion.