nominalize
[ nom-uh-nl-ahyz ]
/ ˈnɒm ə nlˌaɪz /
verb (used with object), nom·i·nal·ized, nom·i·nal·iz·ing.
to convert (another part of speech) into a noun, as in changing the adjective lowly into the lowly or the verb legalize into legalization.
to convert (an underlying clause) into a noun phrase, as in changing he drinks to his drinking in I am worried about his drinking.
Also
especially British,
nom·i·nal·ise.