"Che gelida manina" was an aria from Giacomo Puccini's opera La bohème.

When Data was dating Jenna D'Sora in 2367, he sang the first three lines of the aria for her while cleaning up Jenna's quarters. (TNG: "In Theory")

"Che gelida manina" (first part)
Italian English
Che gelida manina
Se la lasci riscaldar.
Cercar che giova?
Al buio non si trova.
Ma per fortuna
è una notte di luna,
e qui la luna
l'abbiamo vicina.
What a frozen little hand,
let me warm it for you.
What's the use of looking?
We won't find it in the dark.
But luckily
it's a moonlit night,
and the moon
is near us here.