Jounce (?), v. t. & i. [imp. & p. p. Jounced (?); p. pr. & vb. n. Jouncing (?).] [Cf. Jaunce.]
To jolt; to shake, especially by rough riding or by driving over obstructions.
© Webster 1913.
Jounce, n.
A jolt; a shake; a hard trot.