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

1) In a → star cluster, coming across of two stars so closely that their → orbits alter by their mutual → gravitational attractions.
2) As regards an → asteroid or → comet, a situation when it crosses the Moon's orbit and approaches the Earth with a risk of collision. See also → close approach, → encounter.

→ close; → encounter.