some kind of connection, link, or association between two or more entities, especially two companies;
e.g. The two companies have a tie-up by which they share intellectual property and profits.
(noun)
(American) an obstruction or obstacle that slows or stops the flow of traffic, operation, or business;
e.g. She was late because of a tie-up caused by repairs being done to the road.
(noun)
(American) a place where something is temporarily tied up, for example a building where cows are kept for the night or a space for a boat to be moored;
e.g. The boat was docked at the tie-up at the end of the season.