premodify
Concise Oxford English Dictionary © 2008 Oxford University Press:
premodify/priːˈmɒdɪfʌɪ/
▶verb (premodifies, premodifying, premodified) Grammar modify the sense of (a word) by being placed before it.
– derivatives
premodification noun,
premodifier noun.
premodification noun,
premodifier noun.
'premodify' also found in these Oxford entries:

