1. most inclined to growl or make low, threatening sounds; most bad-tempered or irritable
Usage: superlative form of growly

Examples

• The growliest dog in the neighborhood finally warmed up to the mail carrier.
• Dad was at his growliest before his morning coffee.
• Even the growliest customer seemed satisfied with the service.
• The old bear was the growliest creature in the entire zoo.
• She became the growliest person in the office during tax season.
• The growliest engine in the garage belonged to the vintage motorcycle.