A supernumerary or accessory chromosome, one that is not essential for the life of a species and does not occur in all individuals.

(attributive) brightness mode: a common kind of two-dimensional ultrasound image / (attributive) A divergence-free, curl-only polarization signal in the cosmic microwave background radiation.

plural of B-mode

(transportation planning) Transportation for ordinary purposes, as opposed to that by a professional driver for business purposes.

plural of B-scan

plural of B chromosome

An ultrasonographic diagnostic test used in optometry and ophthalmology to produce a two-dimensional, cross-sectional view of the eye and the orbit.

the second most common form of hemophilia, affecting 1/4s of hemophiliacs, caused by a deficiency in clotting factor IX

(linguistics) The western member of the Tocharian branch of Indo-European languages, extinct since the ninth century. Once spoken in the Tarim Basin in Central Asia.

plural of B cell