Concise Bible Dictionary:

Two words are employed in the Hebrew.
2. qadosh, “consecrated, set apart, holy” (Deut. 33:33Yea, he loved the people; all his saints are in thy hand: and they sat down at thy feet; every one shall receive of thy words. (Deuteronomy 33:3); Job 15:1515Behold, he putteth no trust in his saints; yea, the heavens are not clean in his sight. (Job 15:15); Psa. 16:33But to the saints that are in the earth, and to the excellent, in whom is all my delight. (Psalm 16:3); Psa. 34:99O fear the Lord, ye his saints: for there is no want to them that fear him. (Psalm 34:9); Psa. 89:5,75And the heavens shall praise thy wonders, O Lord: thy faithfulness also in the congregation of the saints. (Psalm 89:5)
7God is greatly to be feared in the assembly of the saints, and to be had in reverence of all them that are about him. (Psalm 89:7)
; Dan. 7:18-2718But the saints of the most High shall take the kingdom, and possess the kingdom for ever, even for ever and ever. 19Then I would know the truth of the fourth beast, which was diverse from all the others, exceeding dreadful, whose teeth were of iron, and his nails of brass; which devoured, brake in pieces, and stamped the residue with his feet; 20And of the ten horns that were in his head, and of the other which came up, and before whom three fell; even of that horn that had eyes, and a mouth that spake very great things, whose look was more stout than his fellows. 21I beheld, and the same horn made war with the saints, and prevailed against them; 22Until the Ancient of days came, and judgment was given to the saints of the most High; and the time came that the saints possessed the kingdom. 23Thus he said, The fourth beast shall be the fourth kingdom upon earth, which shall be diverse from all kingdoms, and shall devour the whole earth, and shall tread it down, and break it in pieces. 24And the ten horns out of this kingdom are ten kings that shall arise: and another shall rise after them; and he shall be diverse from the first, and he shall subdue three kings. 25And he shall speak great words against the most High, and shall wear out the saints of the most High, and think to change times and laws: and they shall be given into his hand until a time and times and the dividing of time. 26But the judgment shall sit, and they shall take away his dominion, to consume and to destroy it unto the end. 27And the kingdom and dominion, and the greatness of the kingdom under the whole heaven, shall be given to the people of the saints of the most High, whose kingdom is an everlasting kingdom, and all dominions shall serve and obey him. (Daniel 7:18‑27); Dan. 8:1313Then I heard one saint speaking, and another saint said unto that certain saint which spake, How long shall be the vision concerning the daily sacrifice, and the transgression of desolation, to give both the sanctuary and the host to be trodden under foot? (Daniel 8:13); Hos. 11:1212Ephraim compasseth me about with lies, and the house of Israel with deceit: but Judah yet ruleth with God, and is faithful with the saints. (Hosea 11:12); Zech. 14:55And ye shall flee to the valley of the mountains; for the valley of the mountains shall reach unto Azal: yea, ye shall flee, like as ye fled from before the earthquake in the days of Uzziah king of Judah: and the Lord my God shall come, and all the saints with thee. (Zechariah 14:5)). Aaron is called “the saint of Jehovah” (Psa. 106:1616They envied Moses also in the camp, and Aaron the saint of the Lord. (Psalm 106:16)).
In the New Testament the word used is ἅγιος, which means “holy one.” A saint is one set apart for God; he is such by calling—not “called to be a saint” (Rom. 1:77To all that be in Rome, beloved of God, called to be saints: Grace to you and peace from God our Father, and the Lord Jesus Christ. (Romans 1:7); 1 Cor. 1:22Unto the church of God which is at Corinth, to them that are sanctified in Christ Jesus, called to be saints, with all that in every place call upon the name of Jesus Christ our Lord, both theirs and ours: (1 Corinthians 1:2); compare Heb. 3:11Wherefore, holy brethren, partakers of the heavenly calling, consider the Apostle and High Priest of our profession, Christ Jesus; (Hebrews 3:1)). Saints are thus a distinct, recognized class of persons belonging to God—His saints (Acts 9:1313Then Ananias answered, Lord, I have heard by many of this man, how much evil he hath done to thy saints at Jerusalem: (Acts 9:13); Col. 1:2626Even the mystery which hath been hid from ages and from generations, but now is made manifest to his saints: (Colossians 1:26); 1 Thess. 3:1313To the end he may stablish your hearts unblameable in holiness before God, even our Father, at the coming of our Lord Jesus Christ with all his saints. (1 Thessalonians 3:13); Jude 1:1414And Enoch also, the seventh from Adam, prophesied of these, saying, Behold, the Lord cometh with ten thousands of his saints, (Jude 14)). All Christians are embraced in this class, so that the apostle could speak of “all saints” (Eph. 1:1515Wherefore I also, after I heard of your faith in the Lord Jesus, and love unto all the saints, (Ephesians 1:15); Eph. 3:1818May be able to comprehend with all saints what is the breadth, and length, and depth, and height; (Ephesians 3:18); Col. 1:44Since we heard of your faith in Christ Jesus, and of the love which ye have to all the saints, (Colossians 1:4); Philem. 1:55Hearing of thy love and faith, which thou hast toward the Lord Jesus, and toward all saints; (Philemon 5)). Christians therefore need not shrink from acknowledging the designation by which God has been pleased to distinguish them, and should ever remember that there is a line of conduct that “becometh saints” (Rom. 16:22That ye receive her in the Lord, as becometh saints, and that ye assist her in whatsoever business she hath need of you: for she hath been a succorer of many, and of myself also. (Romans 16:2); Eph. 5:33But fornication, and all uncleanness, or covetousness, let it not be once named among you, as becometh saints; (Ephesians 5:3)). The word ἅγιος corresponds with the Hebrew qadosh. The word chasid corresponds more with ὅσιος, translated “holy” (1 Tim. 2:88I will therefore that men pray every where, lifting up holy hands, without wrath and doubting. (1 Timothy 2:8); Titus 1:88But a lover of hospitality, a lover of good men, sober, just, holy, temperate; (Titus 1:8); Heb. 7:2626For such an high priest became us, who is holy, harmless, undefiled, separate from sinners, and made higher than the heavens; (Hebrews 7:26); Rev. 15:44Who shall not fear thee, O Lord, and glorify thy name? for thou only art holy: for all nations shall come and worship before thee; for thy judgments are made manifest. (Revelation 15:4)); and “Holy One” (Acts 2:2727Because thou wilt not leave my soul in hell, neither wilt thou suffer thine Holy One to see corruption. (Acts 2:27); Acts 13:3535Wherefore he saith also in another psalm, Thou shalt not suffer thine Holy One to see corruption. (Acts 13:35)).

From Anstey’s Doctrinal Definitions:

A saint is a “set apart one” or a “sanctified one.” All who know the Lord Jesus Christ as their Saviour are sanctified (positionally), and thus are saints.
In the KJV, Romans 1:77To all that be in Rome, beloved of God, called to be saints: Grace to you and peace from God our Father, and the Lord Jesus Christ. (Romans 1:7) says, “Called to be saints,” but the words to be are italicized, indicating that they are not in the Greek text and have been added by the translators to aid the reading of the passage. Unfortunately, it changes the meaning and makes sainthood a goal to be attained at some time in the future. (This is a Roman Catholic error. They teach that if a person lives nobly for that system, after he leaves this world through death, he may be promoted to the special place of being a saint.) The text should simply read, "called saints." This means that a person becomes a saint by obeying the gospel call. It is not something we hope to be, but something that the Word of God says that we are by the grace of God. There is no Scripture that tells us to try to attain to sainthood, but there are Scriptures that tell us that all believers are saints, even while they are still living in this world. Nevertheless, some people think that it is a mark of humility to refuse to call themselves a saint now, but it is not pride or presumption to believe the Word of God. In fact, a believer who refuses to call himself a saint is really denying the truth of Scripture.
A “sinner” in Scripture is a person who is not saved. However, when a person is justified, he is cleared from every charge of sin by being brought into a new position before God, wherein God no longer sees him in the position of a sinner, but rather, as a saint. Therefore, for believers to speak of themselves as being poor sinners is beneath the dignity of their position before God. It really denies the truth of what we are as sons of God. In a sense, it demeans the work of Christ which has saved us and set us in that new place of favour as “sanctified in Christ Jesus” (1 Cor. 1:22Unto the church of God which is at Corinth, to them that are sanctified in Christ Jesus, called to be saints, with all that in every place call upon the name of Jesus Christ our Lord, both theirs and ours: (1 Corinthians 1:2)). We are not saying that Christians shouldn't use the term "sinners" in connection with themselves, but that they should say that we were once sinners.
W. Kelly said, "Some people talk of 'a believing sinner,' or speak of the worship offered to God by 'poor sinners.' Many hymns indeed never bring the soul beyond this condition. But what is meant by 'sinner' in the Word of God is a soul altogether without peace, a soul which may perhaps feel its want of Christ, being quickened by the Spirit, but without the knowledge of redemption. It is not truthfulness to deny what saints are in the sight of God" (Lectures on the Epistle to the Galatians, p. 47).
Mr. Kelly also said, "There prevails among too many evangelical persons a mischievous habit of talking about 'saved sinners.' To my mind it is not only inexact but misleading and dangerous. Scripture knows no such thing as a 'saved sinner.' We may rejoice over a 'sinner saved' if we know the mercy of it in our souls; but if we license the phrase—a 'saved sinner,' the moral effect is, that, when and though saved, he is still free to sin....It is perfectly true that, when God begins to deal with a soul, He certainly begins with him as a sinner; but He never ends there. I am not aware of any part of the Word of God in which a believer, save perhaps in a transitional state, is ever referred to as a 'sinner.'....It is evident that to be a saint and sinner at the same time is simply a flat contradiction. In short, Holy Scripture does not sanction such a combination, and the sooner we get rid of such phrases, which deserve no better name than religious cant, the better for all parties" (Lectures Introductory to the New Testament," pp. 213-214).
There is an exception to this in James 5:19-2019Brethren, if any of you do err from the truth, and one convert him; 20Let him know, that he which converteth the sinner from the error of his way shall save a soul from death, and shall hide a multitude of sins. (James 5:19‑20). James calls a failing believer a "sinner," but not in the sense of a positional thing as Paul and Peter use the term. James is rather speaking of what characterizes a believer who persists in following a course of sin in his life.