Moonstruck/ˈmuːnstrʌk/ Definition 1 of 2Pro Tip 1/3Emotionally Intense Used when someone is so affected by feelings they seem irrational or odd. After the proposal, Mia was moonstruck and couldn't focus at work. Pro Tip 2/3Romantic Context Often used in romantic scenarios where love has a strong impact. The way he talks about her, you’d think he's moonstruck. Pro Tip 3/3Positive Nuance Although it may seem negative, it's usually a positive and endearing term. His moonstruck smile was contagious at the wedding.