The word(s) "heedless" appears 14 time(s) in 14 verse(s) in Quran in Mohsin Khan translation.

(1) So We took retribution from them. We drowned them in the sea, because they belied Our Ayat (proofs, evidence, verses, lessons, signs, revelations, etc.) and were heedless about them.

(2) I shall turn away from My Ayat (verses of the Qur'an) those who behave arrogantly on the earth, without a right, and (even) if they see all the Ayat (proofs, evidence, verses, lessons, signs, revelations, etc.), they will not believe in them. And if they see the way of righteousness (monotheism, piety, and good deeds), they will not adopt it as the Way, but if they see the way of error (polytheism, crimes and evil deeds), they will adopt that way, that is because they have rejected Our Ayat (proofs, evidence, verses, lessons, signs, revelations, etc.) and were heedless (to learn a lesson) from them.

(3) And surely, We have created many of the jinn and mankind for Hell. They have hearts wherewith they understand not, and they have eyes wherewith they see not, and they have ears wherewith they hear not (the truth). They are like cattle, nay even more astray; those! They are the heedless ones.

(4) Verily, those who hope not for their meeting with Us, but are pleased and satisfied with the life of the present world, and those who are heedless of Our Ayat (proofs, evidence, verses, lessons, signs, revelations, etc.),

(5) So this day We shall deliver your (dead) body (out from the sea) that you may be a sign to those who come after you! And verily, many among mankind are heedless of Our Ayat (proofs, evidence, verses, lessons, signs, revelations, etc.).

(6) It is not for any person to believe, except by the Leave of Allah, and He will put the wrath on those who are heedless.

(7) They are those upon whose hearts, hearing (ears) and sight (eyes) Allah has set a seal. And they are the heedless!

(8) And keep yourself (O Muhammad صلى الله عليه وسلم) patiently with those who call on their Lord (i.e. your companions who remember their Lord with glorification, praising in prayers, and other righteous deeds) morning and afternoon, seeking His Face; and let not your eyes overlook them, desiring the pomp and glitter of the life of the world; and obey not him whose heart We have made heedless of Our Remembrance, and who follows his own lusts, and whose affair (deeds) has been lost.

(9) Draws near for mankind their reckoning, while they turn away in heedlessness.

(10) And the true promise (Day of Resurrection) shall draw near (of fulfillment). Then (when mankind is resurrected from their graves), you shall see the eyes of the disbelievers fixedly staring in horror. (They will say): "Woe to us! We were indeed heedless of this - nay, but we were Zalimun (polytheists and wrong-doers)."