"paving stone; worn, rounded stone," c. 1600 (earlier cobblestone, q.v.), probably a diminutive of cob in some sense. The verb in this sense is from 1690s. Related: Cobbled; cobbling.
late 15c., "to mend or patch" (especially shoes or boots), perhaps a back-formation from cobbler (n.1), or from cob, via a notion of lumps. Meaning "to put together clumsily" is from 1580s. Related: Cobbled; cobbling.