From The Collaborative International Dictionary of English v.0.48:
Rebuff \Re*buff"\ (r[-e]*b[u^]f"), n. [It. ribuffo, akin to
ribuffare to repulse; pref. ri- (L. re-) + buffo puff. Cf.
Buff to strike, Buffet a blow.]
1. Repercussion, or beating back; a quick and sudden
resistance.
[1913 Webster]
The strong rebuff of some tumultuous cloud.
--Milton.
[1913 Webster]
2. Sudden check; unexpected repulse; defeat; refusal;
repellence; rejection of solicitation.
[1913 Webster]
From The Collaborative International Dictionary of English v.0.48:
Rebuff \Re*buff"\, v. t. [imp. & p. p. Rebuffed
(r[-e]*b[u^]ft"); p. pr. & vb. n. Rebuffing.]
To beat back; to offer sudden resistance to; to check; to
repel or repulse violently, harshly, or uncourteously.
[1913 Webster] re-build