Wiktionary
fishmouth
n. (context roofing English) a half-cylindrical or half-conical shaped opening or void in a lapped edge or seam, usually caused by wrinkling or shifting of ply sheets during installation.
Usage examples of "fishmouth".
Mocsin and the horrible death of his only friend, Fishmouth Charlie, finally and irrevocably tipped the balance of his mind into madness.
The even bigger disadvantage, of course, was that I would have to let old fishmouth do more than kiss me.
I felt none of the disgust I had experienced when old fishmouth had kissed me.
Overcome with questions and admonishments without direction, Alice fishmouthed into silence.