To retch means to make the gagging, heaving motion and sound of trying to vomit, even if nothing actually comes up. Your stomach and throat muscles contract forcefully, your body lurches forward, and you make that distinctive choking sound. You might retch from smelling something truly awful, like spoiled milk or a dumpster on a hot day, or from being sick with a stomach bug.

Retching is your body's automatic response when it detects something potentially harmful. Sometimes retching leads to actual vomiting, but sometimes it's just the motion without anything coming out, which people call dry heaving.

You might read about a character in a book who retches after discovering something disgusting, or hear someone say they were retching all night from food poisoning. It's an unpleasant but useful word for describing that specific, unmistakable bodily reaction.