1) it is necessary, there is need of, it behooves, is right and proper
    1a) necessity lying in the nature of the case
    1b) necessity brought on by circumstances or by the conduct of
        others toward us.
    1c) necessity in reference to what is required to attain some end
    1d) a necessity of law and command, of duty, equity
    1e) necessity established by the counsel and decree of God,
        especially by that purpose of his which relates to the
        salvation of men by the intervention of Christ and which is
        disclosed in the Old Testament prophecies
        1e1) concerning what Christ was destined finally to undergo, his
             sufferings, death, resurrection, ascension

 For Synonyms see entry G5829