The Collaborative International Dictionary
Jouncing
Jounce \Jounce\ (jouns), v. t. & i. [imp. & p. p. Jounced (jounst); p. pr. & vb. n. Jouncing (joun"s[i^]ng).] [Cf. Jaunce.] To jolt; to shake, especially by rough riding or by driving over obstructions.
Wiktionary
jouncing
n. A motion that jounces. vb. (present participle of jounce English)