Definitions: To rejoice, be glad. Intransitive.

Particularly in various constructions, e.g.,
1. With a preposition expressing the cause or occasion of joy: ePI, on, with the dative.

References:

1. Matt. 18:13; Lk. 1:14; 13:17; Acts 15:31; 1 Cor. 16:17; 2 Cor. 7:13; Rev. 11:10; Sept.: Prov. 2:14; Hab. 3:18.

Definitions: Injustice. What is not conformable with justice, what ought not to be, that which is wrong. Related to Adikos, unjust, that which is out of harmony with established usage, what's right and fit, hence injustice, unrighteousness. The result of adiKIa is aDIke-ma, evil doing.

Also, money, as in the context of the parable of Lk. 16:1-9. 1 Cor. 13:6 could be taken as those material things that could be acquired through the employment of falsehood in defrauding others instead of telling the truth.

Definition: To take pleasure with others, hence, to approve, assent to.

1. With the dat. of person.
2. With dat. of thing, in or as to which.
3. Followed by the inf., to be like-minded, well-pleased to do something.

References:

1. Rom. 1:32.
2. Lk. 11:48; Acts 8:1; 22:20.
3. 1 Cor 7:12-13.

Matt. 18:13-- And if he finds (GEne-tai heuREIN) it, I tell you the truth (aME-N LEgo- hyMIN), he is happier about (CHAIrei ep') that one sheep than about the ninety-nine that did not wander off. (NIV)
Alt.:--... believe me he is happier about this one (NAB)
Alt.:--... verily I say unto you, he rejoiceth more of that [sheep] (KJV)
Alt.:--... he feels far happier over this one sheep (TEV)
Alt.:--... if he should chance to find it I assure you he is more delighted over that one than he is over the ninety-nine who never wandered away. (Phillips)

Rom. 1:32--Who knowing the judgment of God, that they which commit such things are worthy of death, not only do the same, but have pleasure in (syneudoKOUsin) them that do them. (KJV)
Alt.:--Who, though they have knowledge of the law of God, ... but give approval to those who do them. (BBE)
Alt.:--... but also give hearty approval to those who practice them. (NASB)
Alt.:--... they not only do them themselves but approve and applaud others who practice them. (AMP)
Alt.:--... did not understand that they who do such things, are worthy of death: and not only they that do them, but they also that consent to them that do them. (DRB)

Barnes: Does not rejoice over the “vices” of other people; does not take delight when they are guilty of crime, or when, in any manner, they fall into sin. It does not find pleasure in hearing others accused of sin, and in having it proved that they committed it. It does not find a malicious pleasure in the “report” that they have done wrong; or in following up that report, and finding it established.

Wicked people often find pleasure in this (Rom 1:32), and rejoice when others have fallen into sin, and have disgraced and ruined themselves. People of the world often find a malignant pleasure in the report, and in the evidence that a member of the Church has brought dishonor on his profession. A man often rejoices when an enemy, a persecutor, or a slanderer has committed some crime, and when he has shown an improper spirit, uttered a rash expression, or taken some step which shall involve him in ignominy.

But love does none of these things. It does not desire that an enemy, a persecutor, or a slanderer should do evil, or should disgrace and ruin himself. It does not rejoice, but grieves, when a professor of religion, or an enemy of religion - when a personal friend or foe has done anything wrong. It neither loves the wrong, nor the fact that it has been done. And perhaps there is no greater triumph of the gospel than in its enabling a man to rejoice that even his enemy and persecutor in any respect does well; or to rejoice that he is in any way honored and respected among people. Human nature, without the gospel, manifests a different feeling; and it is only as the heart is subdued by the gospel, and filled with universal benevolence, that it is brought to rejoice when all people do well.

BT Internet:  cairw, rejoice, be glad

ajdikia, a", f., wrongdoing, evil, sin, injustice

St. John Chrysostom, Homily 33:  Ver. 6. "Rejoiceth not in unrighteousness:" i. e., doth not feel pleasure over those that suffer ill: ...

Seest thou how by degrees love makes her nursling an angel? For when he is void of anger, and pure from envy, and free from every tyrannical passion, consider that even from the nature of man he is delivered from henceforth, and hath arrived at the very serenity of angels.

Adam Clarke:  Verse 6. (10.) Rejoiceth not in iniquity] ou cairei epi th adikia? Rejoiceth not in falsehood, but on the contrary, rejoiceth in the truth: this meaning adikia has in different parts of the Scriptures. At first view, this character of love seems to say but little in its favour; for who can rejoice in unrighteousness or falsity? But is it not a frequent case that persons, who have received any kind of injury, and have forborne to avenge themselves, but perhaps have left it to God; when evil falls upon the sinner do console themselves with what appears to them an evidence that God has avenged their quarrels; and do at least secretly rejoice that the man is suffering for his misdeeds? Is not this, in some sort, rejoicing in iniquity? Again: is it not common for interested persons to rejoice in the successes of an unjust and sanguinary war, in the sackage and burning of cities and towns; and is not the joy always in proportion to the slaughter that has been made of the enemy? And do these call themselves Christians? Then we may expect that Moloch and his sub-devils are not so far behind this description of Christians as to render their case utterly desperate. If such Christians can be saved, demons need not despair!

John Gill's Exposition of the Bible:  Rejoiceth not in iniquity -- Neither in his own, nor in others; but on the contrary is grieved for it; he mourns over his own iniquities, the corruption of his heart, the infirmities of his life, his secret sins, which none know but God and his own soul; he is greatly troubled at the profaneness and immorality of the men of the world, and the sins of professors cut him to the heart: nor does he rejoice in injustice, as the word used here may be rendered, in any unjust action or injury, that may be done to any, yea, even to an enemy; even as Christ, when Peter, in great zeal for him, drew his sword and cut off the ear of one of the high priest's servants, who was more busy than the rest in apprehending Christ, and showed more malignancy than others, was so far from rejoicing at it, that he was displeased with Peter for doing it, and was moved with so much compassion to that man, though his enemy, as to heal him.

John W. Gregson:  "Rejoiceth not in iniquity (chairei adikia) or is not glad when evil happens to someone, ... Those who have love in their hearts are never happy with unrighteousness or evil, for it is opposed to truth. Love does not rejoice in unrighteousness; it is never glad when others go wrong. ...

"Our sources of news tell us that the public will lap up bad and unsavory news. Christian love finds no appeal or joy in this, ..." (Sunday School Times, October 12, 1963, p. 9). There is little good news in our newspapers today; there is plenty of bad news--murders, rapes, robberies, meanness of all kinds.

Matthew Henry:  It rejoiceth not in iniquity. It takes no pleasure in doing injury or hurt to any. It thinks not evil of any, without very clear proof. It wishes ill to none, much less will it hurt or wrong any, and least of all make this matter of its delight, rejoice in doing harm and mischief. Nor will it rejoice at the faults and failings of others, and triumph over them, either out of pride or ill-will, because it will set off its own excellences or gratify its spite. The sins of others are rather the grief of a charitable spirit than its sport or delight; they will touch it to the quick, and stir all its compassion, but give it no entertainment. It is the very height of malice to take pleasure in the misery of a fellow-creature. And is not falling into sin the greatest calamity that can befall one? How inconsistent is it with Christian charity, to rejoice at such fall!

Jamieson, Fausset, & Brown:  Exults not at the perpetration of iniquity (unrighteousness) by others (compare Ge 9:22, 23), ...

The false charity which compromises "the truth" by glossing over "iniquity" or unrighteousness is thus tacitly condemned (Pr 17:15).

BW Johnson:  Rejoiceth not in iniquity. Instead of rejoicing, is filled with sadness by wrong doing of any kind.

Mark Heber Miller:  (Love) does not rejoice over unrighteousness.

The phrase is variously translated: NAS: does not rejoice in unrighteousness; WMS: it is never glad when wrong is done; BAS: takes no pleasure in wrongdoing; NEB: does not gloat over other men’s sins; MOF: it is never glad when others go wrong. The idea has two factors: a) love does not enjoy doing wrong things; or, b) love never takes delight in evil which befalls others.

Jealousy or envy may be involved here. If someone dislikes another and that person falls into trouble, or misfortune visits, the jealous person may rejoice inwardly over this bad turn of events. For example, a wealthy person is the object of envy but one day this person loses all their riches. Love will not motivate a person to say to others, "Well, so-and-so got what’s coming to him." This kind of attitude takes many forms. If we find ourselves to be somewhat happy when evil befalls another, we must look inside and see why we feel this way.

Robertson's Word Pictures: Rejoiceth not in unrighteousness (ou chairei). See Rom 1:32 for this depth of degradation. There are people as low as that whose real joy is in the triumph of evil.

Robertson's Word Studies:  Rejoiceth not in iniquity--Yea, weeps at either the sin or folly of even an enemy; takes no pleasure in hearing or in repeating it, but desires it may be forgotten for ever.

The Theologian: The Internet Journal for Integrated Theology:  In verse 6 adikia is (unexpectedly) parallel to aletheia--the Corinthians ought not to delight in a feeling of superiority over others, but ...

Bill Turner:  Love rejoices not in iniquity, it is not glad when others go wrong.