Frightful (adjective) — مُرعب: Very bad or unpleasant; causing fear. Below are 8 words with a similar meaning; the linked ones have full GL Dictionary entries with their meaning in Arabic.
Extremely bad or unpleasant; causing or involving great suffering, fear, or unhappiness; inspiring dread or fear; terrible in degree or extent
Extremely bad, unpleasant, or shocking; also used informally for a large degree of something undesirable
Causing horror or disgust; very unpleasant.
Causing great horror or fear; very bad.
Causing shock, horror, or deep moral outrage; extremely bad, offensive, or unacceptable — shocking in quality or conduct
terribleshockingfearful
Causing horror; extremely shocking.