The American Heritage® Dictionary of the English Language, 4th Edition
ad. Music To a slight degree or amount; somewhat. Used chiefly as a direction.
the GNU version of the Collaborative International Dictionary of English
ad. A little; -- used chiefly in phrases indicating the time or movement
The Century Dictionary and Cyclopedia
In music, a little; somewhat; rather: as, poco adagio, somewhat slow.
Word Usage
"We met with a friend who, on our complaint, expostulated with him, and said, -- "Señor, these gentlemen say that you drive them very slowly (_muy poco á poco_).""