B19 or B-19 may refer to:
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B19 (New York City bus)
The Metropolitan Transportation Authority (MTA) operates a number of bus routes in Brooklyn, New York, United States; one minor route is privately operated under a city franchise. Many of them are the direct descendants of streetcar lines (see ...
, serving Brooklyn
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Douglas XB-19
The Douglas XB-19 was a four-engined, piston-driven heavy bomber produced by the Douglas Aircraft Company for the United States Army Air Forces (USAAF) during the early 1940s. The design was originally given the designation XBLR-2 (''XBLR'' deno ...
, an experimental bomber aircraft
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Parvovirus B19
Parvovirus B19, also called B19 virus (B19V), Human parvovirus B19, or sometimes erythrovirus B19, is a human virus in the family ''Parvoviridae'', genus ''Erythroparvovirus''. It measures only 23–26 nm in diameter. The virus is assigned ...
, the virus that causes fifth disease
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Caro–Kann Defence
The Caro–Kann Defence is a chess opening characterised by the moves:
:1. e4 c6
The Caro–Kann is a common defence against 1.e4. It is classified as a Semi-Open Game, like the Sicilian Defence and French Defence, although it is thought to b ...
ECO code in chess
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Patient B-19
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Boron-19 (B-19 or
19B), an isotope of boron
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LNER Class B19, classified B2 until 1945
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