Definition from Wiktionary, the free dictionary
The traditional account* states that ㅂ (b) is derived from ㅁ (m) by the addition of a stroke (ㅁ而ㅂ […] 其因聲加畫).
ㅂ • (b)
- 비읍 (bieup, “bieup”), a jamo (letter) of the alphabet of the Korean writing system, hangeul; the unaspirated bilabial plosive (/p/)
In the North Korean order, ㅂ (b) is the sixth jamo. In the South Korean order, it is the eighth.