Definition of cock-block in English:

cock-block

(also cock block)

transitive verb

[with object]vulgar slang US
  • Prevent (someone) from succeeding in their attempt to engage in sexual activity.

    • ‘are you that desperate that you will cock-block your friends so that they don't get any action?’

noun

vulgar slang US
  • A person who prevents someone from succeeding in their attempt to engage in sexual activity.

    • ‘her cock block of a little brother barges into the room’