The term 'wingspans' refers to the distance between the tips of a bird's wings when they are fully extended. It is also used to refer to the length of an aircraft's wingspan, which is the distance from one wingtip to the other. Wingspans are important for both birds and aircraft because they affect the amount of lift generated by the wings. The crossword solution for wingspans is 'SPREADS, ' which accurately describes the action of extending the wings.