SITFAST
Etymology
Noun
sitfast (plural sitfasts)
A callosity with inflamed edges, on the back of a horse, under the saddle.
Adjective
sitfast (not comparable)
Fixed; stationary; immovable.
Source: Wiktionary
Sit"fast`, a. Etym: [Sit + fast.]
Definition: Fixed; stationary; immovable. [R.]
'T is good, when you have crossed the sea and back, To find the
sitfast acres where you left them. Emerson.
Sit"fast`, n. (Far.)
Definition: A callosity with inflamed edges, on the back of a horse, under
the saddle.
Source: Webster’s Unabridged Dictionary 1913 Edition