subtilize
Concise Oxford English Dictionary © 2008 Oxford University Press:
subtilize /ˈsʌtɪlʌɪz/ (or subtilise /ˈsʌtɪlʌɪz/)
▶verb archaic make more subtle; refine.
– derivatives
subtilization noun.
subtilization noun.
'subtilize' also found in these Oxford entries:

