Real Dictionary

largo
Largo written above a piece of music means that it should be played slowly.
countable noun: A largo is a piece of music, especially part of a longer piece, that is played slowly.

Largo in American English
(in a) slow and stately (manner): often used as a musical direction
a largo movement or passage
city in WC Fla.: pop. 69,000
slow; in a broad, dignified style
noun: a largo movement

largo in British English
to be performed slowly and broadly
noun: a piece or passage to be performed in this way