also: ぜんおう
noun
former king; late king
Refers to a previous monarch, either still alive (former) or deceased (late). Context determines which nuance applies.
前王の時代には、この国はもっと平和だった。
In the time of the former king, this country was more peaceful.
前王の葬儀が国葬として行われた。
The late king's funeral was held as a state funeral.
先王 also means 'former/late king' and is more common. 前王 is a less frequent synonym.
Compound of 前 (previous) and 王 (king). The reading ぜんのう is the standard on'yomi combination; ぜんおう is a less common variant.