ḏd(“to say”) + ḥr(“Horus”), thus literally ‘Horus says’. This might be either a shortened form of the name ḏd-ḥr-jw.f-ꜥnḫ(literally “Horus says, ‘He will live’”) or an ancient misreading of a hieratic name ns-ḥr(literally “the one belonging to Horus”).
Leprohon, Ronald (2013) Denise Doxey, editor, The Great Name: Ancient Egyptian Royal Titulary, Atlanta: Society of Biblical Literature, →ISBN, page 172
von Beckerath, Jürgen (1984) Handbuch der ägyptischen Königsnamen, München: Deutscher Kunstverlag, →ISBN, pages 116, 282–283
Ranke, Hermann (1935) Die ägyptischen Personennamen[1], volume 1, Glückstadt: Verlag von J. J. Augustin, page 411.12