Here's how the connection works:
* Block: A physical object used to obstruct passage.
* Blockade: An act of obstructing passage, typically by military forces, to prevent movement of people or goods.
Therefore, the root word "block" directly signifies the core action of a blockade, which is to prevent something from passing through.
This connection makes it easier to remember the definition of "blockade" because it connects the word to a familiar and concrete concept - the act of blocking something.