imitative of the work of another artist, writer, etc., and usually disapproved of for that reason.
an artist who is not in the slightest bit derivative
imitative,unoriginal,uninventive,non-innovative,unimaginative,uninspired,copied,plagiarized,plagiaristic,second-hand,secondary,echoic,trite,hackneyed,clichéd,stale,tired,worn out,flat,rehashed,warmed-up,stock,banal,copycat,cribbed,old hat,hacky
something which is based on another source.
the aircraft is a derivative of the Falcon 20G