single-decker

From single +‎ decker, from deck (“floor, level”).

single-decker (plural single-deckers)

1. (especially UK) a single-deck bus, which has only one level for passengers, unlike a double-decker.

   I travelled home on a crowded single-decker - over half of the passengers were schoolchildren.

• double-decker

• “single-decker”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.