Refers to the choice and arrangement of words, especially in formal or literary contexts. Often used when discussing writing style, rhetoric, or careful expression.
His speech had skillful wording and captivated the audience.
この文章は措辞に注意を払って書かれている。
This text is written with careful attention to diction.
syntax
The exact derivation is uncertain; the kanji 措 (set, place) and 辞 (word, speech) combine to suggest 'placing words', i.e., the careful arrangement of language.