The word(s) "certain" appears 144 time(s) in 135 verse(s) in Quran in Abdullah Yusuf Ali translation.

(11) For the iniquity of the Jews We made unlawful for them certain (foods) good and wholesome which had been lawful for them;- in that they hindered many from Allah's Way;-

(12) O ye who believe! Call in remembrance the favour of Allah unto you when certain men formed the design to stretch out their hands against you, but (Allah) held back their hands from you: so fear Allah. And on Allah let believers put (all) their trust.

(13) As to those who turn (for friendship) to Allah, His Messenger, and the (fellowship of) believers,- it is the fellowship of Allah that must certainly triumph.

(14) If We had made it an angel, We should have sent him as a man, and We should certainly have caused them confusion in a matter which they have already covered with confusion.

(15) Yea, in their own (eyes) will become manifest what before they concealed. But if they were returned, they would certainly relapse to the things they were forbidden, for they are indeed liars.

(16) They say: "Why is not a sign sent down to him from his Lord?" Say: "Allah hath certainly power to send down a sign: but most of them understand not.

(17) They swear their strongest oaths by Allah, that if a (special) sign came to them, by it they would believe. Say: "certainly (all) signs are in the power of Allah: but what will make you (Muslims) realise that (even) if (special) signs came, they will not believe."?

(18) Say: "O my people! Do whatever ye can: I will do (my part): soon will ye know who it is whose end will be (best) in the Hereafter: certain it is that the wrong-doers will not prosper."

(19) Those who give partners (to Allah) will say: "If Allah had wished, we should not have given partners to Him nor would our fathers; nor should we have had any taboos." So did their ancestors argue falsely, until they tasted of Our wrath. Say: "Have ye any (certain) knowledge? If so, produce it before us. Ye follow nothing but conjecture: ye do nothing but lie."

(20) Are they waiting to see if the angels come to them, or thy Lord (Himself), or certain of the signs of thy Lord! the day that certain of the signs of thy Lord do come, no good will it do to a soul to believe in them then if it believed not before nor earned righteousness through its faith. Say: "Wait ye: we too are waiting."