The word(s) "dreadful" appears 12 time(s) in 12 verse(s) in Quran in Abdullah Yusuf Ali translation.

(1) Be not like those who are divided amongst themselves and fall into disputations after receiving Clear Signs: For them is a dreadful penalty,-

(2) Not those who spend of their substance, to be seen of men, but have no faith in Allah and the Last Day: If any take the Evil One for their intimate, what a dreadful intimate he is!

(3) If a man kills a believer intentionally, his recompense is Hell, to abide therein (For ever): And the wrath and the curse of Allah are upon him, and a dreadful penalty is prepared for him.

(4) Or lest ye should say: "If the Book had only been sent down to us, we should have followed its guidance better than they." Now then hath come unto you a clear (sign) from your Lord,- and a guide and a mercy: then who could do more wrong than one who rejecteth Allah's signs, and turneth away therefrom? In good time shall We requite those who turn away from Our signs, with a dreadful penalty, for their turning away.

(5) We sent Noah to his people. He said: "O my people! worship Allah! ye have no other god but Him. I fear for you the punishment of a dreadful day!

(6) "Then will come after that (period) seven dreadful (years), which will devour what ye shall have laid by in advance for them,- (all) except a little which ye shall have (specially) guarded.

(7) Any one who, after accepting faith in Allah, utters Unbelief,- except under compulsion, his heart remaining firm in Faith - but such as open their breast to Unbelief, on them is Wrath from Allah, and theirs will be a dreadful Penalty.

(8) Has then your Lord (O Pagans!) preferred for you sons, and taken for Himself daughters among the angels? Truly ye utter a most dreadful saying!

(9) There is not a population but We shall destroy it before the Day of Judgment or punish it with a dreadful Penalty: that is written in the (eternal) Record.

(10) Say, "The truth is from your Lord": Let him who will believe, and let him who will, reject (it): for the wrong-doers We have prepared a Fire whose (smoke and flames), like the walls and roof of a tent, will hem them in: if they implore relief they will be granted water like melted brass, that will scald their faces, how dreadful the drink! How uncomfortable a couch to recline on!