1. cockblock - Noun
2. cockblock - Verb
(vulgar, slang) To make or attempt to make another's intended goal of romantic relationship or sexual intercourse impossible.
(vulgar, slang, by extension) To prevent someone from achieving a goal, aggressively getting in the way (e.g. an intentionally difficult level of a video game).
(vulgar, slang) The act of cockblocking.
(vulgar, slang) A person who cockblocks.
Source: en.wiktionary.org