What's the difference between jounce and jounced?

Jounce

Definition:

• (v. t. & i.) To jolt; to shake, especially by rough riding or by driving over obstructions.
• (n.) A jolt; a shake; a hard trot.

Example Sentences:

• (1) He motioned for his daughter to stay still and looked through his binoculars at lights jouncing on the shingle.

Jounced

Definition:

• (imp. & p. p.) of Jounce

Example Sentences:

• (1) He motioned for his daughter to stay still and looked through his binoculars at lights jouncing on the shingle.