Meaning

noun an authoritative rule

noun a guiding principle

verb issue commands or orders for

originFirst attested in 1581; borrowed from Latin dictātum (“a thing said, something dictated”), substantivized from the nominative neuter singular of dictātus, the perfect passive participle of dictō (“pronounce or declare repeatedly; dictate”), frequentative of dīcō (“say, speak”). Doublet of diktat.

Etymology from Wiktionary, CC BY-SA 3.0