antagonize
Concise Oxford English Dictionary © 2008 Oxford University Press:
antagonize /anˈtaɡənʌɪz/ (or antagonise)
▶verb
- 1 make hostile.
- 2 Biochemistry act as an antagonist of (a substance).
– origin C18 (in the sense ‘struggle against’): from Gk antagōnizesthai, from ant- ‘against’ + agōnizesthai ‘struggle’.
'antagonize' also found in these Oxford entries:

