• if you have a run-in with someone, you argue or quarrel with them; an informal use.
• a run-in is also a violent struggle or a short armed conflict.
• a run-in is also a rehearsal which takes place just before the actual performance or just before a more important performance.
• the run-in to an event is the period of time or the journey before it.
run in a stocking
• tear through the length of a nylon stocking
run in primaries
• run in the early elections, compete in the first round of elections