A monochrome system of transmitting and receiving television signals. / A television set that displays only monochrome images.

An informal sport in which participants use tyre inner tubes as rafts and ride them on rivers through caves

A tinamou, Crypturellus atrocapillus.

plural of black bag job

(informal) A covert or clandestine entry into a building etc. to obtain information for an intelligence operation.

plural of black bag operation

Synonym of black bag operation

(mathematics, physics) A mathematical formulation for a black hole which does not contain a singularity. The environment outside the event horizon is the same as other formulations for black holes.

A South American duck of freshwater habitats, Heteronetta atricapilla, known for laying its eggs in the nests of other ducks.

plural of black-headed duck