A Tempo Definition
ä tĕmpō
adjective
In the tempo originally designated; resuming the initial tempo of a section or movement after a specified deviation from it. Used chiefly as a direction.
American Heritage
adverb
In time: a note to the performer to return to the preceding tempo.
Webster's New World
Origin of A Tempo
Italian a in tempo time
From American Heritage Dictionary of the English Language, 5th Edition