Fourth Declension (Declinatio Quarta)

The circumflex accent ( ˆ ) is used to denote the length of the vowels.

Fourth declension includes nouns of all the threee genders, the sthem of which ends with –u. For this reason it is called also u- declension.
 

Cases	Singular				Plural
	m	f	n		m	f	n
Nom. Gen. Dat. Acc. Abl. Voc.	fructus fructus fructui fructum fructu fructus	manus manus manui manum manu manus	genu genus genu genu genu genu		fructus fructuum fructibus fructus fructibus fructus	manu manuum manibus manus manibus manus	genua genuum genibus genua genibus genua

Between the most important words of fourth declension are:

acus, us mf needle, pin
arcus, us mf bow, ark
cornu, us n horn, wing of army
domus, us f home, house, fatherland
fructus, us m fruit
gelu, us n frost, ice, snow
genu, us n knee
Jesus, us m Jesus
manus, us f hand
metus, us mf fear, anxiety
motus, us m motion
porticus, us f portico, colonnade
spiritus, us m spirit
tribus, us f third part of the people, tribe

Particularities

The name Jesus has only three declensional forms in singular:
nom. Jesus, gen./dat./abl./voc. Jesu, acc. Jesum.

The noun domus, us f has some doublet forms on the pattern of 2^nd declension: