What word would best describe dialogue that includes archaic phrases?

The term "antiquated language" is best suited to describe dialogue that features archaic phrases. This is because "antiquated" specifically refers to language, words, or phrases that are no longer in common use or have fallen out of favor over time, typically because they belong to an earlier period of history. When dialogue employs archaic phrases, it evokes a sense of history or formality, distinguishing it from modern vernacular.

In contrast, "contemporary language" refers to more current and everyday speech that reflects today’s usage. "Colloquial language" includes informal expressions and slang commonly used in conversation but does not necessarily include archaic expressions. "Technical language" refers to jargon or specialized terminology used in specific fields or professions, which is not relevant to the context of archaic phrases. Thus, "antiquated language" accurately captures the essence of dialogue filled with archaic terms.