驍

Brave or vigorous; an early gloss also says “a good horse.”

The Shuowen Jiezi, an early Chinese character dictionary, glosses it as “a good horse.” Its structure pairs 馬, the horse element, with 堯, the sound element. In Chinese compounds such as 驍勇 and 驍悍, it describes bravery and vigor. Japanese kanji dictionaries also list gyō and kyō (with a long “o”), plus the native Japanese readings tsuyoi (“strong”) and takeshi (“brave”).

Can 驍 stand alone in a message? It can, but alone it names a quality rather than a complete thought; shared context explains why it was sent.