sicken

Concise Oxford English Dictionary © 2008 Oxford University Press:
sicken/ˈsɪkən/

▶verb

• 1 become disgusted or appalled.

  ■ (as adj. sickening) informal very irritating or annoying.

  ■ archaic feel disgust or horror.

• 2 become ill.

  ■ (sicken for) begin to show symptoms of (a particular illness).

– derivatives
sickeningly adverb.