wingspan
n.the distance from one wing to the other when a bird or an airplane has its wings fully spread out.
n.the distance between the tips of the two wings of a bird, insect, or aircraft when fully extended.
“The eagle has a wingspan of over two meters.”
“Engineers had to calculate the wingspan to ensure the aircraft could fit safely within the hangar doors.”
“The fossilized remains of the ancient pterosaur suggest it possessed an impressive wingspan, potentially rivaling that of modern-day albatrosses in terms of aerodynamic efficiency.”
“They're actually quite small birds, about the size of a wood pigeon, but they look much bigger - they have a wingspan much bigger in comparison to most other birds to their body size.”
From wing + span.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.