what is the significance of the title? is there more than one "shrew"?

The term shrew was often used in Shakespeare's time and denoted any woman who stepped outside of her bounds. The word shrew can also mean to chastise or scold. There are definitely a number of shrews in the play. Kate is of course the ultimate shrew; Petrucchio takes on shrewish behavior in order to "tame" her; and the shrew in Bianca appears after the marriage vows are spoken.