bell mouth

bell mouth

[′bel ‚mau̇th]
(design engineering)
A flared mouth on a pipe opening or other orifice.
(engineering)
A defect which occurs during metal drilling in which a twist drill produces a hole that is not a perfect circle.
References in classic literature ?
I was in full career, when I heard the cough right overhead, and jumping back and looking up, beheld a man's head in a tall nightcap, and the bell mouth of a blunderbuss, at one of the first-storey windows.
PG-Series Bore Gages can be used to examine the entire bore for diameter, taper, barrel, bell mouth, out-of-round and lobing.
As a result, a bell mouth can be produced at the top of a threaded hole.