دیروز

Persian دیروز means “yesterday.” The دی part is an ancient Persian word for “what has gone past.” That archaic root keeps the time grid intact.

What it actually means

دیروز means “yesterday” in Persian. It is one of three core time words in the native Persian time grid: دیروز (yesterday), امروز (today), فردا (tomorrow). The word is a compound: دی (di-, an archaic Persian particle meaning “passed, gone”) plus روز (rūz, “day”). So دیروز literally reads “the gone day.” The construction also produces دیشب (dīshab, “last night”) and دیر (dīr, “late”), all using the same archaic دی root. Modern Iranians use دیروز freely without thinking about its compound origin. The word slots into time expressions easily: دیروز صبح (yesterday morning), دیروز عصر (yesterday afternoon / evening), پریروز (the day before yesterday).

How to say it

دیروز is invariant. The pronunciation occasionally softens to “diroz” in fast Tehrani speech, but the form does not change in writing. The word triggers the past tense in any sentence it appears in: “دیروز رفتم” (yesterday I went), never “دیروز می‌رم” (which would be a time-tense mismatch).

In a sentence

Cultural note

دیروز is built from دی (di-), an Old Persian particle that survives in modern Persian as a “preceding-time” marker. The same particle produces دیشب (dīshab, “last night,” literally “passed-night”), دیر (dīr, “late,” “delayed”), and دی‌ماه (the Iranian month corresponding to December and January, the “passing” month of winter solstice). Persian’s native time vocabulary is one of its oldest preserved word clusters, dating back to Old Persian inscriptions from the Achaemenid period (6th century BCE). While Persian later borrowed Arabic words for hours, minutes, and seconds (ساعت, دقیقه, ثانیه), the core day-words stayed Persian. This is consistent with how languages typically retain their oldest most-used vocabulary even after borrowing extensively in other domains. The pattern of compound time words (دیروز, امروز, فردا as “this/that/ahead day”) also makes Persian time vocabulary feel like a small grid you can master in one sitting.

Related

You will see this word in conversation with its time-set siblings امروز (today) and فردا (tomorrow). For the long view of how Persian time words have stayed stable across millennia, see 2,500 years of Persian.