What is a one horse carriage called?

A one-horse carriage is typically called a "buggy".

Here are some other names, depending on the specific type:

* Sulky: A lightweight, two-wheeled carriage used for racing.

* Cart: A simple, open carriage with two wheels.

* Gig: A small, two-wheeled carriage for one or two people.

* Phaeton: A four-wheeled carriage with a folding top.

* Surrey: A four-wheeled carriage with a fixed top.

The term "buggy" is the most common and general term for a one-horse carriage.