noun, noun which may take the genitive case particle 'no'
epistolary language; language used in letter writing
Refers to the style, vocabulary, and conventions typical of written correspondence. Often used in discussions of traditional or formal letter-writing.
My grandmother's letters use beautiful epistolary language.
I'm reading old collections of correspondence to learn epistolary expressions.
書き言葉 is written language in general, whereas 文言葉 is narrower, referring to the style used in letters.
Compound of 文 (ふみ, 'letter') and 言葉 (ことば, 'language'). The reading ふみ for 文 is an older native Japanese word for 'letter' or 'written message'.