1.NounThe regnal year, reign period, or regnal title used when traditionally numbering years in an emperor's reign and naming certain Sinospheric rulers."The posthumous names of early Chinese rulers were often variations of a few words like "the martial one" 武 (wǔ), "the literary one" 文, "the filial one" 孝 (xiào), but by the Tang they had become so long that people began using rulers' temple names or era names instead."