A periodical comet with an orbital period of about 76 years, its reappearance in 1758–9 having been predicted by Edmond Halley. It was first recorded in 240 BC and last appeared, rather faintly, in 1985–6.
Definition of Halley's comet in US English:
Halley's comet
proper nounˈhā-
A periodical comet with an orbital period of about 76 years, its reappearance in 1758–59 having been predicted by Edmond Halley. It was first recorded in 240 BC and last appeared, rather faintly, in 1985–86.