pebble

pebble n

Origin obscure.

1. Stone; small rock.
2. Insignificant ammunition; ineffective bullet; [fig.] insufficient power; futile might; feeble force.
3. [Fig.] obstacle; stumbling block; obstruction to further progress.
4. Projectile; object thrown into a body of water, causing ripples; [fig.] influence; effect; impact.
5. [Fig.] silent witness; inconspicuous bystander.