1) the head, both of men and often of animals. Since the loss of the
    head destroys life, this word is used in the phrases relating to
    capital and extreme punishment.
 2) metaph. anything  supreme, chief, prominent
    2a) of persons, master lord: of a husband in relation to his wife
    2b) of Christ: the Lord of the husband and of the Church
    2c) of things: the corner stone