1. to undermine or negatively interfere with sth
sabotage the operation/work/project
To 'sabotage' something is to intentionally destroy, damage or obstruct something, especially for political or military reasons. To ruin something intentionally is to 'sabotage' something. You can sabotage a project, a plot or sabotage a plan, for example. 'A sabotage' as a noun is an act of sabotaging something. This is a formal expression used more in professional contexts.