gasp
To take a sudden, sharp breath from surprise or shock.
To gasp means to take a sudden, sharp breath, usually because something has surprised, shocked, or scared you. When you gasp, air rushes quickly into your lungs through your open mouth, making an audible sound. You might gasp when cold water hits your skin, when someone jumps out and startles you, or when you witness something astonishing.
People also gasp when they're struggling to breathe, like after running hard in a race or when laughing so much they can barely catch their breath. A swimmer coming up from underwater gasps for air. Someone climbing steep stairs might be gasping for breath by the time they reach the top.
The word can be a noun too: you might hear a gasp from the audience when a magician performs an incredible trick, or gasps of surprise when a teacher announces an unexpected field trip. That collective intake of breath reveals the moment when everyone realizes something remarkable or shocking has happened.