- (transitive, idiomatic) To start something with somebody else. Usually a conversation or relationship.
- To make him feel welcome, she struck up a conversation with the newly arrived guest.
- He struck up a friendship with Redford that was to last for many years.
- (intransitive, idiomatic) To start something, usually playing live music.
- The band struck up and everyone started to dance.
- (ergative)The bride entered the church just as the "Wedding March" struck up.