Fettle/ˈfetl/ Definition 1 of 2Pro Tip 1/3Healthiness Hint Often used to express being in good health or high spirits, especially in physical terms. After a week of rest, she was back in fine fettle. Pro Tip 2/3Physical Activity Used to describe someone's fitness related to physical activity, like sports or manual labor. He's in great fettle after that gym session. Pro Tip 3/3Emotional State Can imply good mental or emotional state, though it's primarily about physical condition. She's in high fettle today, nothing can bring her down!