What does « Loss / Failure » mean in the Quran?

And I will mislead them, and I will arouse in them [sinful] desires, and I will command them so they will slit the ears of cattle, and I will command them so they will change the creation of Allah." And whoever takes Satan as an ally instead of Allah has certainly sustained a clear loss.

This day [all] good foods have been made lawful, and the food of those who were given the Scripture is lawful for you and your food is lawful for them. And [lawful in marriage are] chaste women from among the believers and chaste women from among those who were given the Scripture before you, when you have given them their due compensation, desiring chastity, not unlawful sexual intercourse or taking [secret] lovers. And whoever denies the faith - his work has become worthless, and he, in the Hereafter, will be among the losers.

O my people, enter the Holy Land which Allah has assigned to you and do not turn back [from fighting in Allah 's cause] and [thus] become losers."

And his soul permitted to him the murder of his brother, so he killed him and became among the losers.

And those who believe will say, "Are these the ones who swore by Allah their strongest oaths that indeed they were with you?" Their deeds have become worthless, and they have become losers.

Say, "To whom belongs whatever is in the heavens and earth?" Say, "To Allah." He has decreed upon Himself mercy. He will surely assemble you for the Day of Resurrection, about which there is no doubt. Those who will lose themselves [that Day] do not believe.

Those to whom We have given the Scripture recognize it as they recognize their [own] sons. Those who will lose themselves [in the Hereafter] do not believe.

Those will have lost who deny the meeting with Allah, until when the Hour [of resurrection] comes upon them unexpectedly, they will say, "Oh, [how great is] our regret over what we neglected concerning it," while they bear their burdens on their backs. Unquestionably, evil is that which they bear.

Those will have lost who killed their children in foolishness without knowledge and prohibited what Allah had provided for them, inventing untruth about Allah. They have gone astray and were not [rightly] guided.

And those whose scales are light - they are the ones who will lose themselves for what injustice they were doing toward Our verses.

They said, "Our Lord, we have wronged ourselves, and if You do not forgive us and have mercy upon us, we will surely be among the losers."

Do they await except its result? The Day its result comes those who had ignored it before will say, "The messengers of our Lord had come with the truth, so are there [now] any intercessors to intercede for us or could we be sent back to do other than we used to do?" They will have lost themselves, and lost from them is what they used to invent.

Said the eminent ones who disbelieved among his people, "If you should follow Shu'ayb, indeed, you would then be losers."

Those who denied Shu'ayb - it was as though they had never resided there. Those who denied Shu'ayb - it was they who were the losers.

Then did they feel secure from the plan of Allah? But no one feels secure from the plan of Allah except the losing people.

And when regret overcame them and they saw that they had gone astray, they said, "If our Lord does not have mercy upon us and forgive us, we will surely be among the losers."

Whoever Allah guides - he is the [rightly] guided; and whoever He sends astray - it is those who are the losers.

[This is] so that Allah may distinguish the wicked from the good and place the wicked some of them upon others and heap them all together and put them into Hell. It is those who are the losers.

[You disbelievers are] like those before you; they were stronger than you in power and more abundant in wealth and children. They enjoyed their portion [of worldly enjoyment], and you have enjoyed your portion as those before you enjoyed their portion, and you have engaged [in vanities] like that in which they engaged. [It is] those whose deeds have become worthless in this world and in the Hereafter, and it is they who are the losers.

And on the Day when He will gather them, [it will be] as if they had not remained [in the world] but an hour of the day, [and] they will know each other. Those will have lost who denied the meeting with Allah and were not guided

And never be of those who deny the signs of Allah and [thus] be among the losers.

Those are the ones who will have lost themselves, and lost from them is what they used to invent.

Assuredly, it is they in the Hereafter who will be the greatest losers.

[Noah] said, "My Lord, I seek refuge in You from asking that of which I have no knowledge. And unless You forgive me and have mercy upon me, I will be among the losers."

He said, "O my people, have you considered: if I should be upon clear evidence from my Lord and He has given me mercy from Himself, who would protect me from Allah if I disobeyed Him? So you would not increase me except in loss.