A single-decker is a type of bus or train carriage that has only one level. There are several synonyms that can be used to describe a single-decker. One alternative is a "low-floor" bus, which typically has a single step or no step at all, making it easier for passengers to board and alight. Another synonym is a "coach," which is often used to describe a luxury single-decker bus used for long-distance travel. A "city bus" or "municipal bus" is another synonym used to describe a single-decker that is designed for use on urban routes. Other synonyms include "regular bus," "standard bus," and "passenger bus".