1.VerbTo start something with somebody else, such as 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."
2.VerbTo start something, usually playing live music.
"The band struck up and everyone started to dance.; The bride entered the church just as the "Wedding March" struck up."
3.VerbTo raise (as sheet metal), in making dishes, pans, etc., by blows or pressure in a die.