To be tactful means to handle delicate situations with care and sensitivity, saying or doing things in ways that avoid hurting people's feelings or making things awkward. A tactful person knows how to tell the truth without being harsh, or how to disagree without starting an argument.

When your friend shows you a drawing they're proud of but it's not their best work, a tactful response might be “I love how you used color here” rather than “That doesn't look like a real horse at all.” You're being honest about what works without crushing their enthusiasm. When a teacher needs to correct a student who gave a wrong answer in class, a tactful teacher might say “That's an interesting idea, but let's think about it another way” instead of “No, you're completely wrong.”

Tact is the noun form: we'd say that teacher “showed great tact” in that situation. Being tactful doesn't mean lying or hiding the truth. It means finding the right words and the right moment to communicate something, especially when feelings are involved. A tactful person thinks before speaking and considers how their words will land on someone else. The opposite would be being tactless or blunt, where you might say exactly what you think without considering whether it will hurt someone unnecessarily.