lexicology

/L EH0 K S IH0 K AA1 L AH0 JH IY0/
noun
  1. 1

    The part of linguistics that studies words, their nature and meaning, words' elements, relations between words including semantic relations, words groups and the whole lexicon.

  2. 2

    A specific theory concerning the lexicon.

Source: https://en.wiktionary.org/wiki/lexicology