chock-a-block
UK[ˌtʃɒk əˈblɒk]US[ˌtʃɑːk əˈblɑːk]
adj
Completely full; crammed tightly together.
adv
In a way that is completely full or tightly packed.
Etymology
The term 'chock-a-block' originates from 19th-century nautical jargon. It describes the state of two blocks (pulleys) in a ship's tackle system when they are pulled so close together that they touch, or are 'chock' (a variant of 'choke') against each other, preventing further movement. The phrase 'chock and block' was used literally to describe this mechanical state of being jammed tight. Over time, it evolved into the reduplicated form 'chock-a-block' and transitioned from a specific technical description to a general adjective and adverb, signifying any space or situation that is completely packed or full to capacity.
Analysis
This is a reduplicative compound, a type of word formed by repeating or altering a sound. 'Chock' and 'block' are both English words, but their combination is idiomatic and not productively segmentable into meaningful morphemes in the modern sense.
Examples
The parking lot was chock-a-block with cars for the festival.
She packed the suitcase chock-a-block, leaving no room for anything else.
During the holiday sale, the stores were chock-a-block with shoppers.