Monoplan

Part of speech: noun

Definitions

1. An aircraft that has just one set of wings, mounted on one side of the fuselage rather than stacked in pairs
2. A fixed-wing flying machine whose lifting surface consists of a single main wing rather than a biplane arrangement
3. A type of airplane built with one wing structure, as opposed to the two-tiered wings found on biplanes

Etymology: Before the aeroplane had a settled design, "plane" already meant a flat surface. It comes from Latin "planus", "flat", which reached English through French "plan" and gave us the geometric plane. In early aviation, a wing was pictured as a flat sheet, so a flying machine's lifting surfaces were its planes. The prefix "mono-" comes from Greek "monos", meaning "single" or "alone". Put together, a monoplane is a machine with a single set of wings. The term is a compound built to contrast with "biplane", which describes the two-winged design that dominated the period when the single-winged type was new. The exact date and route of the first English use are not something I can confirm, so the term's early history is best read as a coinage made from familiar parts rather than a single documented event.