Chronograms

Part of speech: noun

Definitions

1. Inscriptions or sentences in which certain letters, read as Roman numerals, spell out a particular year or date
2. Phrases or inscriptions whose capital letters double as numerals so that they reveal a specific year when added up
3. Lettered mottoes or verses in which selected letters carry numerical value, forming a date when read together

Etymology: A chronogram is a sentence or phrase in which certain letters, usually written as Roman numerals and picked out in a larger or different style, add up to a date. The trick works because Latin letters double as numbers: M, D, C, L, X, V and I each carry a value, so a motto can quietly record the year it was made. Readers who knew the code could spot the date hidden in plain sight, and the form was prized in inscriptions on churches, bells, and medals, where a single line could both praise and date a building. The word itself is built from Greek. "Chronos" meant "time," and "gramma" meant "writing" or "letter," so the compound, through the combining form "chrono-" and the suffix "-gram," literally means something like "time-writing." The pieces are ancient, but the combination is a modern coinage, so the Greeks themselves had no word for a date concealed in letters.