noun

• (lexicography, linguistics) A dictionary that includes or focuses on lexemes.
  "Sluiter examines a tension inherent in such scholarly works as lexica, scholia, epitomai, and commentaries: although the very titles of these works claim no more than secondary status, their authors engage nonetheless in a rhetoric of self-legitimation."
• (programming) The lexicology of a programming language. (Usually called lexical structure.)
• (rare) Any dictionary.

verb

• (transitive) To add to a lexicon.
  "Vocab-wise, medalling and PB-ing are now totally part-and-parcelled, and most experts in South Korea believe podiumed, finalled and all-comered are not far off lexiconing."
• (film) To shorten a soundtrack to fit a shortened version of a movie.
  "Mrazek’s legislation would discourage time compression, a technique used to speed up a movie, and “lexiconing,” a process of altering the soundtrack to match the shorter, compressed version."