How did Classical written Latin differ from ordinary spoken Latin?

Classical written Latin and ordinary spoken Latin differed significantly in their structure, vocabulary, and stylistic complexity. During the Classical period, written Latin was a highly standardized, sophisticated idiom that emphasized elegance, clarity, and balance. In contrast, ordinary colloquial Latin—often referred to as the sermo plebeius or "plebeian speech"—was more elliptical, featuring shorter, less complex sentences and a more colorful vocabulary that frequently utilized diminutives.12

Key differences included:

• Grammar: Classical Latin relied on synthetic constructions with precise case endings. Spoken Latin increasingly favored analytic constructions, where prepositions replaced case endings to simplify the language.32
• Vocabulary: While Classical prose rejected "vulgarity" and "rusticity," spoken Latin preferred popular terms over sober classical ones (e.g., portare "to carry" was preferred over the classical ferre).13
• Syntax: Classical Latin enforced rigid rules and complex sentence structures, whereas spoken Latin tended toward simpler, more direct phrasing and less flexible word order.32
• Phonology: Spoken Latin was characterized by a strengthening of stress accents, leading to the shortening or loss of unaccented syllables, a process that eventually diverged from the strict vowel-length distinctions essential to Classical poetry.32