He overstepped his station and styled himself emperor.
Tips
history
Not a free word in modern Chinese; it survives in literary compounds — 僭越 (to overstep one's authority) and 僭主 (a usurper-ruler, the term for a Greek tyrant). The right side 朁 is the phonetic, also seen in 潜 and 替.
register
Formal and literary; it appears in history and political writing, rarely in everyday speech.
