Cosmic Synchro Monster refers to a series of Dragon Synchro Monsters that are evolved forms of either "Stardust Dragon" or "Red Dragon Archfiend" used by both Yusei Fudo and Jack Atlas in the Yu-Gi-Oh! 5D's anime. Their names, and thus their "Cosmic Synchro Monster" title, are derived from a space phenomena.
The ATK of "Shooting Star Dragon" and "Red Nova Dragon" are 500 points less than their "Majestic" forms, while their DEF is equivalent to their original form's ATK. "Shooting Quasar Dragon" was later revealed in the anime, as was "Cosmic Blazar Dragon", although the latter was only mentioned and not actually seen.
This name of this series arose from the description on Starstrike Blast booster boxes.