Definition of "lexis"

lexis

/ˈlɛksɪs/

noun
countable and uncountable, plural lexises or lexes or lexeis
1. (linguistics) The set of all words and phrases in a language; any unified subset of words from a particular language.
  Quotations
  Thus, alongside current lexis, words and senses now obsolete find a place in a dictionary on historical principles.
  2018, James Lambert, “Anglo-Indian slang in dictionaries on historical principles”, in World Englishes, volume 37, page 249
2. (pedagogy, TEFL) Words, collocations, and common phrases in a language; vocabulary and word combinations.
  Quotations
  By the 1980s, English language teachers generally had begun to realize that there had been a neglect of lexis in teaching methods and coursebooks. […] The basic truth that without vocabulary or lexis we can't express anything had to be restated and a new approach to teaching lexis was needed.
  2014, Paul Lindsay, Teaching English Worldwide, page 346
3. The vocabulary used by a writer