B19 or B-19 may refer to: B19 (New York City bus), serving Brooklyn Douglas XB-19, an experimental bomber aircraft Parvovirus B19, the virus that causes fifth disease Caro–Kann Defence ECO code in chess Patient B-19 Boron-19 (B-19 or 19B), an isotope of boron LNER Class B19, classified B2 until 1945
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).