Definition of girthing:
(n) :
(informal) One's waistline circumference, most often a large one.
(n) :
A band passed under the belly of an animal, which holds a saddle or a harness saddle in place.
(n) :
The part of an animal around which the girth fits.
(n) :
The distance measured around an object; the circumference.
(v) :
To bind as if with a girth or band.
(n) :
A small horizontal brace or girder.