A small tail-like structure on a comet that, unlike most comet tails, seems to point toward the Sun. This rare event is an optical illusion due to larger dust particles left along the comet's orbit. And typically occurs when the Earth crosses the plane of the comet's orbit. It seen when the observer is in the plane of the cometary orbit.
Antitail, from → anti- "opposite, opposing, against" + → tail.
Pâddom, from pâd-, → anti-, + dom "tail."