Where does “letter” come from?

I need to work through this chain carefully, but I notice there's a significant problem: the chain provided doesn't actually connect "letter" to "let" in English, and the sequence doesn't form a coherent etymological path. Looking at the chain: - English let - Chinese 兒 - Latin littera - Multiple Latin entries (-are, -arius, -us) - Proto-Italic -os This chain is incoherent. "Letter" in English comes from Latin *littera*, not from "let." The chain seems to mix unrelated etymologies. Additionally, Latin *littera* doesn't derive from Chinese 兒, and the presence of multiple Latin suffixes (-are, -arius, -us) without clear word stems makes this impossible to trace logically. I cannot write an accurate one-sentence origin summary because the etymological chain provided is fundamentally broken and doesn't support a

letter (English): A symbol in an alphabet; A written or printed...