severe

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”
• “;”

very strong or vigorous

• “strong winds”
• “a hard left to the chin”
• “a knockout punch”
• “a severe blow”

severely simple

• “a stark interior”

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”

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”

very bad in degree or extent

• “a severe worldwide depression”
• “the house suffered severe damage”