The present meaning (filled to capacity or overloaded) derives from a nautical term. The derivation of chock isn't entirely clear, but the word is thought to have come from chock-full (or "choke-full"), meaning "full to choking." This meaning was later used to name the wedges of wood used to secure moving objects. On sailing ships, a block and tackle pulley system was used to hoist the rigging. The phrase chock-a-block describes what occurs when the system is raised to its fullest extent, i.e., when there is no more rope free and the blocks jam tightly together.
The present meaning (filled to capacity or overloaded) derives from a nautical term. The derivation of chock isn't entirely clear, but the word is thought to have come from chock-full (or "choke-full"), meaning "full to choking." This meaning was later used to name the wedges of wood used to secure moving objects. On sailing ships, a block and tackle pulley system was used to hoist the rigging. The phrase chock-a-block describes what occurs when the system is raised to its fullest extent, i.e., when there is no more rope free and the blocks jam tightly together.