On who pretends to be what he is not.
M.Fr. imposteur, from L.L. impostor, agent noun from impostus, from imponere "to place upon, impose upon, deceive," from → in- "into, in, on, upon" + ponere "to put place," → position.
Daqalkâr, from daqal "imposture, deceit" + -kâr, agent noun suffix, from kardan, → -or.
Fr.: supernova imposteuse
A brilliant burst of light that would suggest a → supernova explosion, but analysis of the star's → light curve, → spectrum, and → luminosity rules it out as a genuine supernova. Energetic → outbursts of → massive stars are often labeled as "supernova impostors" (Van Dyk et al. 2000). Many of these giant eruptions are spectroscopically similar to → Type II-n supernovae and thus receive a supernova (SN) designation, but are later recognized as subluminous or their spectra and light curves do not develop like true supernovae. Consequently, they are often referred to as "supernova impostors." These impostors or giant eruptions are examples of high → mass loss episodes apparently from evolved massive stars. Authors often refer to them as → Luminous Blue Variables (LBVs), but these giant eruptions are distinctly different from LBV/→ S Doradus variability in which the star does not increase in luminosity and the eruption or maximum light can last for several years. The mechanisms triggering these events are not yet fully understood (see, e.g., Humphreys et al., 2016, arXiv:1606.04959v1).