1. One who warns; an admonisher.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• wamer,
• wwner,
• iorner,
• wierner,
• warre,
• warnt,
• werwer,
• waher,
• warnng,
• wayer,
• warnth,
• waggner,
• wiiner,
• warfear,
• harnor,
• wahser,
• warnet,
• weener,
• warror,
• warnin

• warrener,
• Wernert,
• Werner,
• Warriner,
• warmer.

The adjective form of the word "warner" is not commonly used. However, you could possibly use "warning" as an adjective to describe someone or something that gives warnings or alerts.

The plural of the "warner" can be the "warners".

The singular of the "warner" can be the "warner".