Nouns: Gender and agreement

Nouns: Gender and agreement
Gender and number
NOUNS ("sostantivi") can have two GENDERS ("generi"), masculine and feminine, and two NUMBERS, singular and plural.

Generally speaking, masculine nouns end in "-o" (plural "-i") and feminine nouns end in "-a" (plural "-e"):
"il libro" <the book>, "i libri" <the books>;
"la casa" <the house>, "le case" <the houses>.
There are exceptions:
Some feminine nouns end in "-o". they either form the plural in "-i":
"la mano" <the hand>, "le mani" <the hands>;
or (if foreign loanwords ) remain unchanged,
"la foto" <the photograph>, "le foto" <the photographs>.
Some masculine nouns end in "-a"; they form their plural in "-i":
"il problema" <the problem>, "i problemi" <the problems>.
Some masculine nouns change their gender to feminine in the plural, with a singular-type "-a" ending rather than the usual plural form "-e":
"l'uovo" <the egg> BUT "le uova" <the eggs>;
"il dito" <the finger> BUT "le dita" <the fingers>.