The Collaborative International Dictionary
Tempo rubato
Tempo \Tem"po\, n. [It., fr. L. tempus. See Tense, n.] (Mus.) The rate or degree of movement in time.
A tempo giusto (j[=oo]s"t[-o]) [It.], in exact time; -- sometimes, directing a return to strict time after a tempo rubato.
Tempo rubato. See under Rubato.
Wikipedia
Tempo rubato
Tempo rubato (free in the presentation, Italian for: stolen time) is a musical term referring to expressive and rhythmic freedom by a slight speeding up and then slowing down of the tempo of a piece at the discretion of the soloist or the conductor. Rubato is an expressive shaping of music that is a part of phrasing.