pꜣ(“the”) + sbꜣ(“star”) + ḫꜥ(“appearing”) + n(“in”) + nwt(“city”), thus literally ‘the star appearing in the city’, a reference to Thebes.
Greek Ψουσέννης reflects late shift of /ḫ/→[ʃ] in [pəsiwˈʃeʕənneːʔə]. The preposition m appears as n due to assimilation with nwt.
Pronunciation
Lua error in Module:parameters at line 290: Parameter 1 should be a valid language or etymology language code; the value "Late Egyptian" is not valid. See WT:LOL and WT:LOL/E.IPA(key): /pəʔ ˈsiːβə χeʕ nəʔ ˈneːwə/
Ranke, Hermann (1935) Die ägyptischen Personennamen[1], volume 1, Glückstadt: Verlag von J. J. Augustin, page 117.1
Leprohon, Ronald (2013) Denise Doxey, editor, The Great Name: Ancient Egyptian Royal Titulary, Atlanta: Society of Biblical Literature, →ISBN, pages 139, 141, 143
von Beckerath, Jürgen (1984) Handbuch der ägyptischen Königsnamen, München: Deutscher Kunstverlag, →ISBN, pages 98–100, 253–256