glass jaw
noun
1.
a person's jaw, especially that of a boxer, that is vulnerable to even a light blow.
Origin
1910-15
British Dictionary definitions for
glass jaw
glass jaw
noun
1.
(
boxing
,
informal
) a jaw that is excessively fragile or susceptible to punches
Slang definitions & phrases for
glass jaw
glass jaw
noun phrase
A boxer's chin that cannot tolerate a hard punch
(1920+ Prizefight)