Definition
A fixed-wing aircraft with two main wings stacked one above the other, typically connected by struts and bracing wires. The two-wing configuration produces more lift for a given wingspan and allows a stronger, lighter structure than a single wing of the same era's materials, at the cost of higher drag.
Plain English
An airplane with two sets of wings, one above the other, instead of just one.
Context Anchor
Seen in aviation history, aircraft recognition, and discussions of early airplane design.
Derivation
From the Latin 'bi-' meaning 'two' and 'planum' meaning 'flat surface' -- the early word for a wing was 'plane,' referring to a flat lifting surface. So a biplane is literally an aircraft with 'two wings.'
Why Pilots Care
Most modern training and transport aircraft are monoplanes (one wing), but biplanes still appear in aerobatic and agricultural flying. Knowing the term helps a pilot recognize the design and understand why early aircraft, like the Wright Flyer, were built this way -- to gain lift and structural strength when materials were weak.
Intuition Check
Do not read biplane as simply “an old airplane.” The key idea is the two main wings stacked one above the other.
Example Sentence 1
The Wright Brothers' 1903 Flyer was a biplane, with two cloth-covered wings braced by wires and wooden struts.
Example Sentence 2
Early pilots often trained in restored biplanes because the design offers good low-speed handling.