Wizarding publisher located at 18a Diagon Alley, London. Their editor Augustus Worme commissioned the original edition of Fantastic Beasts and Where to Find Them by Newt Scamander in 1918, which is now in its 52nd edition (FB).
"obscure" = little-known
It is revealed in the screenplay for Fantastic Beasts and Where to Find Them that Newt Scamander had an interest in helping children with repressed magical ability rid themselves of a Dark internal force known as an "Obscurus." Whether there is a connection between "Obscurials" and the name of Newt's publisher is unknown at this time.