Toothy/ˈtuːθi/ Definition 1 of 2Pro Tip 1/3Facial Expressions Used to describe a smile or grin that reveals several or all of one's teeth. The baby's toothy smile melted her heart. Pro Tip 2/3Positive Emotion Often conveys warmth, friendliness, or genuine happiness. His toothy grin made everyone in the room cheerful. Pro Tip 3/3Slightly Informal This adjective is casual and might not be suitable for very formal texts. She was greeted by the dog's enthusiastic, toothy welcome.