severe

Unsparing and uncompromising in discipline or judgment.

“a parent severe to the pitch of hostility”

“a hefty six-footer with a rather severe mien”

Severely simple.

Intensely or extremely bad or unpleasant in degree or quality.

“severe pain”

“a severe case of flu”

Very strong or vigorous.

“a severe blow”

Causing fear or anxiety by threatening great harm.

“a severe case of pneumonia”

Very bad in degree or extent.

“a severe worldwide depression”

“the house suffered severe damage”