The Collaborative International Dictionary of English v.0.48:

Reboant \Re*bo"ant\ (r[-e]*b[=o]"ant), a. [L. reboans, p. pr. of
   reboare; pref. re- re- + boare to cry aloud.]
   Rebellowing; resounding loudly. [R.] --Mrs. Browning.
   [1913 Webster]