Source : Webster's Revised Unabridged Dictionary (1913)

Severe \Se*vere"\, a. [Compar. {Severer}; superl. {Severest}.]
   [L. severus; perhaps akin to Gr. ??? awe, ??? revered, holy,
   solemn, Goth. swikns innocent, chaste: cf. F. s['e]v[`e]re.
   Cf. {Asseverate}, {Persevere}.]
   1. Serious in feeeling or manner; sedate; grave; austere; not
      light, lively, or cheerful.

            Your looks alter, as your subject does, From kind to
            fierce, from wanton to severe.        --Waller.

   2. Very strict in judgment, discipline, or government; harsh;
      not mild or indulgent; rigorous; as, severe criticism;
      severe punishment. ``Custody severe.'' --Milton.

            Come! you are too severe a moraler.   --Shak.

            Let your zeal, if it must be expressed in anger, be
            always more severe against thyself than against
            others.                               --Jer. Taylor.

   3. Rigidly methodical, or adherent to rule or principle;
      exactly conformed to a standard; not allowing or employing
      unneccessary ornament, amplification, etc.; strict; --
      said of style, argument, etc. ``Restrained by reason and
      severe principles.'' --Jer. Taylor.

            The Latin, a most severe and compendious language.
                                                  --Dryden.

   4. Sharp; afflictive; distressing; violent; extreme; as,
      severe pain, anguish, fortune; severe cold.

   5. Difficult to be endured; exact; critical; rigorous; as, a
      severe test.

   Syn: Strict; grave; austere; stern; morose; rigid; exact;
        rigorous; hard; rough; harsh; censorious; tart;
        acrimonious; sarcastic; satirical; cutting; biting;
        keen; bitter; cruel. See {Strict}. -- {Se*vere"ly}, adv.
        -- {Se*vere"ness}, n.

Source : WordNet®

severe
     adj 1: intensely or extremely bad or unpleasant in degree or
            quality; "severe pain"; "a severe case of flu"; "a
            terrible cough"; "under wicked fire from the enemy's
            guns"; "a wicked cough" [syn: {terrible}, {wicked}]
     2: very strong or vigorous; "strong winds"; "a hard left to the
        chin"; "a knockout punch"; "a severe blow" [syn: {hard}, {knockout}]
     3: severely simple; "a stark interior" [syn: {austere}, {stark}]
     4: unsparing and uncompromising in discipline or judgment; "a
        parent severe to the pitch of hostility"- H.G.Wells; "a
        hefty six-footer with a rather severe mien"; "a strict
        disciplinarian"; "a Spartan upbringing" [syn: {spartan}, {strict}]
     5: causing fear or anxiety by threatening great harm; "a
        dangerous operation"; "a grave situation"; "a grave
        illness"; "grievous bodily harm"; "a serious wound"; "a
        serious turn of events"; "a severe case of pneumonia"; "a
        life-threatening disease" [syn: {dangerous}, {grave}, {grievous},
         {serious}, {life-threatening}]
     6: very bad in degree or extent; "a severe worldwide
        depression"; "the house suffered severe damage"