s as z.

Properly, short and thick, like a clump or lump. Hence,

Moving heavily, slowly or awkwardly; as clumsy fingers.

Awkward; ungainly; unhandy; artless; without readiness, dexterity or grace; as a clumsy man; a clumsy fellow.

\Ill-made; badly constructed; as a clumsy garment; clumsy verse.