girth

UK: /ˈgɜː^rθ/ US: /gɝθ/ ,(gûrth)

WordReference Random House Learner's Dictionary of American English © 2025

girth /gɜrθ/  also girt, n. 

1. the measure around a body or object;
   circumference:
   [countable] The girth of that huge tree was several yards.
   [uncountable] The tree was several yards in girth.
2. size;
   bulk:
   [uncountable] a man of huge girth.
3. [countable] a band that passes underneath a horse or other animal to secure a saddle.

WordReference Random House Unabridged Dictionary of American English © 2025

girth  (gûrth), n. 

1. the measure around anything;
   circumference.
2. a band that passes underneath a horse or other animal to hold a saddle in place, esp. one having a buckle at each end for fastening to straps running from under the flaps of the saddle. See illus. under saddle. 
3. something that encircles;
   a band or girdle.

v.t. 

4. to bind or fasten with a girth.
5. to girdle;
   encircle.

Also, girt. 

• Old Norse gerth girdle; akin to gird¹
• Middle English girth, gerth 1300–50

Collins Concise English Dictionary © HarperCollins Publishers::

girth / ɡɜːθ/ noun

1. the distance around something; circumference
2. a band around a horse's belly to keep the saddle in position

verb

1. (usually followed by up) to fasten a girth on (a horse)
2. (transitive) to encircle or surround

Etymology: 14th Century: from Old Norse gjörth belt; related to Gothic gairda girdle¹; see gird¹