tight-lipped
adjectiveUK /ˌtaɪt ˈlɪpt/
US /ˌtaɪt ˈlɪpt/
Not saying anything about something.
The coach stayed tight-lipped about who would play in the final.
OTHER MEANINGS
2. Keeping your lips pressed firmly together, often because you are angry.
She sat tight-lipped while the others argued.
3. Refusing to reveal information that others want to know.
The company was tight-lipped about its new product.
4. Showing anger or disapproval without speaking.
He gave a tight-lipped nod and walked away.