Haddan \ha(d)-dan\ as a boy's name is a variant of Hadden (Old English), and the meaning of Haddan is "hill of heather".

The baby name Haddan sounds like Haddin, Haddon and Haydan. Other similar baby names are Haldan, Hadrian, Hanan, Hadar, Hadon, Haden, Hadwin, Hadwyn, Haggan, Hagan, Haidar, Haydar, Hakan, Halden, Haldane, Haylan, Harden, Hardon, Hardin, Hassan, Hasan, Hayden, Haydon, Haydn, Kaydan, Kaidan, Kadan, Caydan and Caidan.