Definitions:

1. To be kind, obliging, willing to help or assist.

Definitions:

Profitable, fit, good for any use. ...

(II) Of persons,

1. Useful toward others, hence good-natured, good, gentle, kind.
2. to chre-STON (neuter gender with the article), goodness, kindness. Equal to he- chre-STOte-s.

References:

1. Luke 6:35; 1 Cor 13:4; Eph. 4:32; 1 Pet 2:3.
2. Rom. 2:4; Septuagint: Ps. 86:5.

Definitions: Benignity, kindness, usefulness.

1. Goodness.
2. Kindness.
3. Gentleness.

It is the grace which pervades the whole nature, mellowing all which would be harsh and austere. Like wine, mellowed with age (cf. Luke 5:39). The word is descriptive of one's disposition and does not necessarily entail acts of goodness.

References:

1. Rom. 3:12.
2. 2 Cor. 6:6; Eph. 2:7; Col. 3:12; Titus 3:4.
3. Gal. 5:22.

Definitions:

1. Gracious, agreeable. Said of a wife who brings glory to her husband.
2. Grateful, thankful.

References:

1. Prov. 11:16 (Septuagint).
2. Col. 3:15.

Definitions:

1. Objective, that which bestows or occasions pleasure, delight, or causes favorable regard.
2. Subjective,
   1. On the part of the bestower, the friendly disposition from which the kindly act proceeds, graciousness, lovingkindness, goodwill.
   2. On the part of the receiver, a sense of the favour bestowed, a feeling of gratitude.
3. In another objective sense, the effect of grace, the spiritual state of those who have experienced its exercise.

References:

1. Luke 2:40; 2 Cor 8:6; Luke 4:22; Col. 4:6.
2. Acts 7:10; Acts 14:26; Rom. 4:4,16; 11:6; John 1:17; Rom. 6:14,15; Gal. 5:4.
3. Rom. 6:17; Luke 17:9; 1 Tim. 1:12.
4. Rom. 5:2; 1 Pet. 5:12; 2 Pet. 3:18; 1 Cor. 16:3; 2 Cor. 8:6,19; 9:8; Rom. 1:5; 12:6; 15:15; 1 Cor. 3:10; Gal. 2:9; Eph. 3:2,7; etc.

Luke 6:35-- But love (agaPAte) your enemies, do good (agathopoiEIte) to them, and lend to them without expecting to get anything back (me-DEN apelPIzontes). Then your reward will be great, and you will be sons of the Most High, because he is kind (chre-STOS) to the ungrateful (achaRIStous) and the wicked. 36 Be merciful (GInesthe oikTIRmones), just as your Father is merciful (oikTIRmo-n esTI). (NIV)
Alt.:--... You will rightly be called sons of the Most High, since he himself is good (NAB)
Alt.:--... to the ungrateful and the selfish. (RSV)
Alt.:--Love your enemies! Do good to them! Lend to them! And don't be concerned about the fact that they won't repay. Then your reward from heaven will be very great, and you will truly be acting as sons of God: for he is kind to the unthankful and the very wicked. (LB)

Romans 2:[3-]4-- ... when you, a mere man, pass judgment on [someone else] and yet do the same things, do you think you will escape God's judgment? 4 Or do you show contempt for (kataphroNEIS) the riches of his kindness (chre-sTOte-tos), tolerance (anoCHE-S), and patience (makrothyMIas), not realizing that God's kindness (chre-sTON) leads you towards repentance (meTAnoian)? (NIV)
Alt.:--... Or do you despise the riches of His goodness, forbearance, and long-suffering, not knowing that the goodness of God leads you to repentance? (KJV)
Alt.:-- 4 Or do you presume on his kindness and forbearance? Do you not know that God's kindness is an invitation to you to repent? (NAB)
Alt.:-- 4 ... Surely you know that God is kind, because he is trying to lead you to repent. (TEV)
Alt.:-- 4 ... Do you not know that God's kindness is meant to lead you to repentance? (RSV)
Alt.:--Do you think that God will judge and condemn others for doing them and overlook you when you do them, too? 4 Don't you realize how patient he is being with you? Or don't you care? Can't you see that he has been waiting all this time without punishing you, to give you time to turn from your sin? (LB)
Alt.:--What makes you think that you, who so readily judge the sins of others, can consider yourself beyond the judgment of God? Are you, perhaps, misinterpreting God's generosity and patient mercy toward you as weakness on his part? (Phillips)

Eph. 4:32-- Be kind (chre-sTOI) and compassionate (EUsplanchnoi) to one another, forgiving each other, just as in Christ God forgave you. (NIV)
Alt.:--And be kind to one another, tenderhearted, (KJV)
Alt.:--In place of these, be kind to one another, compassionate, and mutually forgiving, just as God has forgiven you in Christ. (NAB)
Alt.:--But become kind to one another, tenderly compassionate, freely forgiving (NWT)
Alt.:--Be kind to one another; be understanding. (Phillips)

St. John Chrysostom, Homily 33:  But Paul doth not stop here, but adds also the other high achievements of love, saying, "is kind." For since there are some who practise their long-suffering with a view not to their own self-denial, but to the punishment of those who have provoked them, to make them burst with wrath; he saith that neither hath charity this defect. Wherefore also he added, "is kind." For not at all with a view to light up the fire, in those who are inflamed by anger, do they deal more gently with them, but in order to appease and extinguish it: and not only by enduring nobly, but also by soothing and comforting, do they cure the sore and heal the wound of passion.

Adam Clarke:  Is kind] crhsteuetai? It is tender and compassionate in itself, and kind and obliging to others; it is mild, gentle, and benign; and, if called to suffer, inspires the sufferer with the most amiable sweetness, and the most tender affection. It is also submissive to all the dispensations of God; and creates trouble to no one.

John Gill's Exposition of the Bible:  and is kind; liberal, and bountiful, does good to all men, even to enemies, and especially to the household of faith; he is gentle to all men, affable and courteous to his brethren, and not morose, churlish, and ill natured; he is easy and yielding to the tempers and humours of men; accommodates himself to their infirmities, capacities, manners, and circumstances, in everything he can, that is not contrary to the glory of God, the interest of Christ, the honour of religion, his own con science, and the good of men.

Matthew Henry:  It is kind--chresteuetai. It is benign, bountiful; it is courteous and obliging. The law of kindness is in her lips; her heart is large, and her hand open. She is ready to show favours and to do good. She seeks to be useful; and not only seizes on opportunities of doing good, but searches for them. This is her general character. She is patient under injuries, and apt and inclined to do all the good offices in her power. And under these two generals all the particulars of the character may be reduced.

Jamieson, Fausset, & Brown:  is kind--the positive side. Extending good to others. Compare with love's features here those of the "wisdom from above" (Jas 3:17).

Mark Heber Miller:  (Love is) kind.

The Greek KHRESTEETAI is variously rendered: RHM: gracious; PME: it looks for a way to be constructive; but, most use the English "kind." The Middle English root KYNDE means sympathetic, friendly, gentle, tender-hearted, generous. The Greek is a rare word in the Christian Bible, occurring only here in 1 Corinthians 13:4b. Related forms occur about 70 times. Christ’s yoke is kind. (Matthew 11:30) God is kind even toward the unthankful and wicked and thus kindness and mercy are the path to godly perfection. (Luke 6:35; Matthew 5:45) Kindness is often associated with hospitality and giving. (Acts 26:2, 30; 2 Corinthians 8:6, 7, 9) God is characterized by kindness. (Romans 2:4; Titus 3:4; 1 Peter 2:3) Paul elsewhere counsels kindness. (Ephesians 4:32; Colossians 3:12) Kindness is a fruit of the spirit. (Galatians 5:22) Of course, kindness is related to "grace" which is really undeserved kindness.

So, kindness, or being kind, would be characterized by hospitality, charity, giving, mercy, and good manners, or gentility (a word rooted in the old English related to KYNDE).

Someone has said, "When in doubt about what to do to another --do the kind thing." Our Christianity should be characterized by our kindness, particularly toward even our enemies, those unthankful, or even wicked. Only then can spiritual perfection be attained. (Matthew 5:43-48; Luke 6:30-36)

Robertson's Word Studies:  {Is kind} (cresteuetai). From crestos (useful, gracious, kind) and that from craomai, to use. Not found elsewhere save in Clement of Rome and Eusebius. "Perhaps of Paul's coining" (Findlay). Perhaps a vernacular word ready for Paul. Gentle in behavior.

The Theologian: The Internet Journal for Integrated Theology:  Kresteuetai is the other side of patience, the active response. Love is slow to anger, and quick to repay evil with kindness, rather than with revenge. Love is not skilled in delivering devastating one-line put-downs whenever it is confronted with a personal attack, although given the alleged Corinthian love for slogans, the Corinthian Christians probably were.

Bill Turner:  "Chresteuetai," is the present middle of "chresteuomai," to be gentle, benign, and kind in behaviour and service to others; from "chrestos," useful, kind, gracious, gentle (like Christ's yoke in Mt.11v30.). Origen says it means, "Sweet to all ." Though "chrestos" occurs elsewhere, (Mt.11v30. Lk.5v39. 6v35. Rom.2v4. 1Cor.15v33. Eph.4v32. 1Pet.2v3.), "chresteuomai" only appears here in the New Testament, it speaks of a gracious, kind and gentle behaviour. Love not only suffers long with people who are a trial to its patience, it is kind to them and does them good in a positive manner. The present tense again shows the continuous nature and habit of this constructive kindness.

Vincent's Word Studies:  Is kind (crhsteuetai). Only here in the New Testament. See on crhstov, A.V., easy, Matt. xi. 30, and crhstothv good, Rom. iii. 12. "The high charity which makes us servants Prompt to the counsel which controls the world." DANTE, "Paradiso," xxi., 70, 71.