Definition of antitail in English:

antitail

Pronunciation /ˈantɪteɪl/

noun

Astronomy
  • A luminous protuberance which appears to extend from a comet's head towards the sun.

    An antitail is actually the comet’s tail (or part of it), extending away from the sun but appearing to point towards it as a result of a perspective effect when the comet is seen from a certain angle. Compare earlier "beard".

Origin

1950s. From anti- + tail.