basic form vs lexical item

basic form

noun
  • The uninflected form of a word used as a dictionary entry. 

lexical item

noun
  • A term—word or a sequence of words—that acts as a unit of meaning, including words, phrases, phrasal verbs and proverbs, exemplified by cat, traffic light, take care of, by-the-way, and don't count your chickens before they hatch. 

How often have the words basic form and lexical item occurred in a corpus of books? (source: Google Ngram Viewer )