girthn.[Icel. gjr girdle, or ger girth; akin to Goth. garda girdle. See Gird to girt, and cf. Girdle, n.]1. A band or strap which encircles the body; especially, one by which a saddle is fastened upon the back of a horse.()2. The measure around any object, such as a body at the waist or belly, or a box ; the circumference of anything; as, in order to be acceptable for mailing, the total of height and girth of a package must not exceed 63 inches.()He's a lusty, jolly fellow, that lives well, at least three yards in the girth. (Addison.)3. A small horizontal brace or girder.()v. t.[From Girth, n., cf. Girt, v. t.] To bind as with a girth.(Johnson.)