Translation guide
The word 'lexicon' refers to the vocabulary of a language, a person, or a specialized field. In Japanese, different terms are used depending on whether you mean a dictionary-like list, the mental vocabulary, or the vocabulary of a particular domain.
Referring to the entire set of words in a language or a specialized domain.
The most common and general term for 'vocabulary' or 'lexicon'. It can refer to the words of a language, a person, or a field.
日本語の語彙は豊富だ。
The Japanese lexicon is rich.
専門用語の語彙を増やす必要がある。
I need to expand my technical lexicon.
Specifically a glossary or collection of terms, often for a specific field. More like a 'terminology list' than a mental lexicon.
この医学用語集は便利だ。
This medical lexicon is useful.
Means 'dictionary'. Sometimes used loosely to refer to a lexicon as a reference work, but it's not the mental lexicon.
彼は生きた辞書だ。
He is a walking lexicon.
Referring to the words that a particular person knows or uses.
Same word as above, but used in the context of an individual's vocabulary.
彼女は語彙が豊富だ。
She has a rich lexicon.
読書は語彙を増やす。
Reading expands your lexicon.
Referring to a physical or digital book that lists words and their meanings.
Standard word for dictionary. Can be used for any language.
英和辞書を引く。
I consult an English-Japanese lexicon.
Often used in titles of dictionaries, especially specialized ones. Slightly more formal than 辞書.
Older, colloquial term for dictionary. Literally 'character puller'. Rarely used today.
字引で調べなさい。
Look it up in the lexicon.
Referring to the mental repository of words and their properties in linguistic theory.
Direct loanword used in linguistics. Refers to the abstract mental lexicon.
生成文法ではレキシコンが重要な役割を果たす。
In generative grammar, the lexicon plays an important role.
A more technical term meaning 'lexical inventory'. Used in academic contexts.
この言語の語彙目録を作成する。
We compile the lexicon of this language.
語彙 (ごい) refers to vocabulary or the mental lexicon, while 辞書 (じしょ) is a physical or digital dictionary. Don't use 辞書 when you mean someone's vocabulary.
彼の語彙はすごい。
His lexicon is amazing.
辞書で単語を調べる。
I look up words in a lexicon (dictionary).
Loanword from English, often used in educational contexts or casual speech. Slightly more colloquial than 語彙.
ボキャブラリーを増やしたい。
I want to increase my lexicon.
I bought a Japanese lexicon.