The Collaborative International Dictionary of English v.0.48:
Bunch \Bunch\, v. i. [imp. & p. p. Bunched; p. pr. & vb. n.
Bunching.]
To swell out into a bunch or protuberance; to be protuberant
or round.
[1913 Webster]
Bunching out into a large round knob at one end.
--Woodward.
[1913 Webster]