Noun and の adjective
げんさく
マンガが原作の映画は、原作の良さを失ってしまうことが多いです。
Comic book movies often lose the flavor of the original work.
シェイクスピアを原作で読んだことはありますか？
Have you read Shakespeare's original works?
この漫画は、テレビアニメとドラマの原作です。
This manga was made into a TV anime and drama series.
The original thing you make is the original work. It's always better to have the original, rather than a copy, I think.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.