| Ace |
| A military aviator or airman credited with shooting down five or more enemy aircraft. |
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| Aerodrome |
| The place "where...aeroplanes are landed and kept and cared for and where the pilots live and start... their trips over the lines... a smooth field covered with sod and occupying a situation near a town and good highway. It is on comparatively level ground and is square in shape and each of the four sides is about half a mile in length." |
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| Aeronaut |
| A person practising air flights by a "lighter-than-air" medium. |
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| Aeronautics |
| The science of air navigation by "lighter-than-air" mediums. |
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| Aeronef |
| A cigar-shaped, motor driven balloon. |
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| Aerostat |
| A free spherical balloon. |
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| Aircraft |
| Any form of craft designed for the navigation of the air. |
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| Airship |
| A motor-driven balloon of elongated form; should not be applied to "heavier-than-air" craft. |
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| Altimeter |
| A direct-reading instrument used for measuring altitude. |
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| Anchor |
| A device for stopping the balloon when landing in a wind, or holding it fast. |
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