(television) An analogue composite video signal with a black picture, used as a reference signal to synchronise timings.

(idiomatic, intransitive) To start laughing suddenly and intensely.

(astronomy) A flash of gamma rays that seem to originate from a random point in the sky; their most likely sources are believed to be supernova explosions of a very massive stars and mergers of neutron stars.

(idiomatic) To disillusion; to disabuse someone of a false notion or rationalization that has grown comfortable.

(idiomatic) A final effort, a final attempt before stopping.

(astronomy) A tight band of radio-frequency waves that lasts only a millisecond, which packs the energy of millions of years of Solar output.

(figuratively) Become so furious that one loses control.

(idiomatic) To start crying uncontrollably and intensely.