The Collaborative International Dictionary
mutandum
mutandum \mu*tan"dum\ (m[-u]*t[a^]n"d[u^]m), n.; pl. Mutanda (m[-u]*t[a^]n"d[.a]). [L., fr. mutare to change.] A thing which is to be changed; something which must be altered; -- used chiefly in the plural.
Wiktionary
mutandum
n. That which is to be changed.