Minor addendum: it seems to be a defective fourth declension. The plural should still be Iesūs. - Edit 2
Before modification by Tom at 02/11/2011 01:05:15 AM
The genitive and dative forms are irregular, probably due to following the Greek, and are both Iesu (from Greek Ιησου, which appears to have an irregular dative identical to the genitive). However, it is certainly considered fourth declension (and second declension in Greek, along the general pattern of νους).
The full declension should be:
Nom. Iesus/Iesūs
Gen. Iesu/Iesuum
Dat. Iesu/Iesubus
Acc. Iesum/Iesūs
Abl. Iesu/Iesubus
I avoided the -ibus variant based on the singular forms which have an overdominating "u".
The full declension should be:
Nom. Iesus/Iesūs
Gen. Iesu/Iesuum
Dat. Iesu/Iesubus
Acc. Iesum/Iesūs
Abl. Iesu/Iesubus
I avoided the -ibus variant based on the singular forms which have an overdominating "u".