For example, these multi-word expressions or lexical units can be listed in their very base forms on thefreedictionary.com:
leave one's mark leave mark on develop from develop from someone develop fight shy of fight shy of something be fighting shy of doing something be out of one's shell
instead of any of their variations like the following:
leave his mark left mark on developing from developed from a painfully shy girl developed fighting shy of fight shy of controversy was fighting shy of cheating is out of your shell
I know that they are not the idioms(as idioms may include possessive pronouns), stems(as stems include subwords), lemmas(as lemmas also include pronouns), or lexemes(also include pronouns; and 'is' and 'be' are two different lexemes) of their inflections or variations.
I wonder if such a very base form has a terminology? I want to normalize the variations into their most base units. Possessive pronouns should become forms like "one's" which cannot be further normalized.