In generative syntax, A-bar movement (or A ′-movement) is movement to an A-bar position (e.g. wh-movement). As is well known, unbounded dependencies are a characteristic property of A ′-movement （Huang et al., 2009).
The term was first used in the late 1980s.
Huang, C. T. J., Li, Y. H. A., & Li, Y. (2009). The syntax of Chinese (Vol. 10). Cambridge: Cambridge University Press.