tie-in /ˈtaɪˌɪn/noun 3tie in verb 3forms 5 noun3 •Something that is related or connected to another thing. •An authorized product based on a media property, such as a film or video game, by way of cross-promotion.Brand new for this season! I got the unrecognizable summer movie tie-in sammich! — 2008 •An association or connection between things. tie in verb3 •To fit in or harmonize (with something).This paragraph does not tie in with the greater themes of the story. •To attach oneself to a rope using a secure knot. •For a local station to begin broadcasting an ongoing network transmission.I believe Argentina has a network of about 20 or 25 stations that they can tie in. — 1938 formstied in · tying in · ties in · tie ins · tie-ins