Appulses is a rare word that refers to a celestial event where two celestial bodies come into close proximity without actually colliding. There are several synonyms for appulses, including conjunction, perigee, and near approach. Conjunction refers to the alignment of two celestial objects, such as planets or stars, in the sky. Perigee, on the other hand, refers to the point in an object's orbit when it is closest to Earth. Near approach is a more generic term that can refer to any type of close encounter between celestial objects. While these terms are not exact synonyms for appulses, they all describe celestial events where objects come near each other in space.