A21, A-21 or A.21 may refer to:
* A road in the
List of A21 roads
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a21, Inc., an American stock-photography company
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The A21 Campaign
The A21 Campaign (commonly referred to as "A21") is a global 501(c)(3) non-profit, non-governmental organization that works to fight human trafficking, including sexual exploitation and trafficking, forced slave labor, bonded labor, involuntary do ...
, a non-profit, non-governmental organization that combats human trafficking, slave and bonded labor, involuntary domestic servitude, and child soldiery
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Aero A.21, a 1920s-era Czechoslovakian military aeroplane
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Arrows A21, a Formula One car
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British NVC community A21 (Ranunculus baudotii community), a plant community
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Focke-Wulf A 21, a photographic survey variant of the 1927 German Focke-Wulf A 17
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Stearman XA-21
The Stearman XA-21 (Model X-100) was a competitor in a United States Army Air Corps competition for a twin-engined attack aircraft which (after redesigns) led to the Douglas A-20 Havoc, Martin A-22 Maryland and North American B-25 Mitchell.
De ...
, a twin-engine American attack bomber
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A21 (chess opening), a code for the English Opening in chess
{{Letter-Number Combination Disambiguation