girth /ɡɜːθ $ ɡɜːrθ/ BrE AmE noun [countable]
[ Date: 1300-1400 ; Language: Old Norse ; Origin: gjörth ]
1 . the size of something or someone large when you measure around them rather than measuring their height:
the enormous girth of the tree
He was a tall man, of considerable girth (=he was fat) .
2 . a band of leather which is passed tightly around the middle of a horse to keep a ↑ saddle or load firmly in position