From The Collaborative International Dictionary of English v.0.48 [gcide]:
Loggia \Log"gia\, n. [It. See Lodge.] (Arch.)
A roofed open gallery. It differs from a veranda in being
more architectural, and in forming more decidedly a part of
the main edifice to which it is attached; from a porch, in
being intended not for entrance but for an out-of-door
sitting-room.
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
loggia
n 1: a roofed arcade or gallery with open sides stretching along
the front or side of a building; often at an upper level