to convert (another part of speech) into a noun, as in changing the adjective lowly into the lowly or the verb legalize into legalization.
2.
to convert (an underlying clause) into a noun phrase, as in changing he drinks to his drinking in I am worried about his drinking.
Nominalization is a type of word formation in which a verb or an adjective (or other part of speech) is used as (or transformed into) a noun. Verb: nominalize. Also called nouning.