noun
lexicology
Academic term for the study of vocabulary, including word formation, meaning, and usage.
語彙論は言語学の一分野です。
Lexicology is a branch of linguistics.
意味論 is 'semantics', the study of meaning, which overlaps with lexicology but focuses on meaning in general.
Compound of 語彙 (goi, 'vocabulary') + 論 (ron, 'theory' or 'study'). The exact historical derivation is uncertain, but the term follows the pattern of academic disciplines ending in 論.