An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) Full of risk; perilous; risky.
2. Dependent on chance (Dictionary.com).

Adj. from → hazard.

An asteroid that could make a threatening close approach to the Earth. In technical terms a PHA is defined as having an → absolute magnitude of 22 or brighter and an → Earth Minimum Orbit Intersection Distance (MOID) of less than 0.05 → astronomical unit or 7.5 million km.

→ potentially; → hazardous; → asteroid.