The phrase "most chock-a-block" means that something is filled or crowded to the maximum. There are several synonyms that convey the same meaning such as jam-packed, crammed, stuffed, brimming, overflowing, teeming, bursting, overflowing, and full to the brim. These words can be used interchangeably depending on the context of the situation. For instance, a stadium can be described as jam-packed while a room may be referred to as crammed. In summary, having a variety of synonyms for a word makes it easier to convey the intended message effectively, making writing and communication more effective.