From BiblePortal Wikipedia

Holman Bible Dictionary [1]

Several Hebrew words are rendered “enemy” in the Old Testament. Tsar means an “adversary, foe, oppressor, or enemy.” It comes from the verb tsarar, which means “to show hostility toward.” An ohev is “one who is hostile, an enemy or foe.” The term sane' means, “one who hates.” Zur is a “stranger, foreigner, or alien.” One Greek term, echthros, is used for each of the Hebrew words in the New Testament. Its basic definition is simply “enemy.”

In the Old Testament enemy generally referred to the national enemies of Israel. These included most of their neighboring nations at one time or the other. The enemies of Israel often were considered the enemies of God, for Israel was God's nation ( Exodus 23:22 ). This view is also espoused by many of the prophets. Though the word “enemy” is not used there, the first chapter of Amos is a classic example of this.

Enemy is also used to speak of one's personal foes. This is especially true in the Psalms. David asked for help against his enemies on a number of occasions ( Psalm 25:2 ,Psalms 25:2, 25:19 ). Other poets in the Psalter often sought this same protection ( Psalm 119:84 ,Psalms 119:84, 119:86 ).

In the New Testament enemy most often refers to one's personal enemies, for the nation of Israel was no longer a force on the political scene. But it also was used of strangers and foreigners in general.

The natural inclination of all people is to hate their enemies. Some have even misconstrued God's law to teach hatred. Jesus taught rather to love one's enemies and to seek their good ( Matthew 5:43-47 ). This is also the teaching of the Old Testament ( Proverbs 24:17;  Proverbs 25:21 ).

In the Bible, a person who disobeys divine commands is declared to be God's enemy. Paul referred to sinners as the enemies of God ( Romans 5:10 ). Job felt that God had become his enemy, too ( Job 13:24 ). Because of this severed relationship, God has made provision for our forgiveness in the life, death, and resurrection of Jesus Christ.

Satan is also called “the enemy” ( 1 Timothy 5:14-15 ). He has revealed himself as such throughout history by seeking to hurt men and women, leading them away from God.

The greatest and final enemy is death itself ( 1 Corinthians 15:24 ). It is feared by all because of its finality and unknown nature. But the Bible teaches that Jesus has “abolished” death once for all ( 2 Timothy 1:10 ). Death need not be feared by those who have trusted Christ for the salvation He freely gives.

Bradley S. Butler

Vine's Expository Dictionary of NT Words [2]

1: Ἐχθρός (Strong'S #2190 — — echthros — ekh-thros' )

an adjective, primarily denoting "hated" or "hateful" (akin to echthos, "hate;" perhaps associated with ektos, "outside"), hence, in the Active sense, denotes "hating, hostile;" it is used as a noun signifying an "enemy," adversary, and is said (a) of the Devil,  Matthew 13:39;  Luke 10:19; (b) of death,  1—Corinthians 15:26; (c) of the professing believer who would be a friend of the world, thus making himself an enemy of God,  James 4:4; (d) of men who are opposed to Christ,  Matthew 13:25,28;  22:44;  Mark 12:36;  Luke 19:27;  20:43;  Acts 2:35;  Romans 11:28;  Philippians 3:18;  Hebrews 1:13;  10:13; or to His servants,  Revelation 11:5,12 : To the nation of Israel,  Luke 1:71,74;  19:43; (e) of one who is opposed to righteousness,  Acts 13:10; (f) of Israel in its alienation from God,  Romans 11:28; (g) of the unregenerate in their attitude toward God,  Romans 5:10;  Colossians 1:21; (h) of believers in their former state,  2—Thessalonians 3:15; (i) of foes,  Matthew 5:43,44;  10:36;  Luke 6:27,35 :  Romans 12:20;  1—Corinthians 15:25; of the Apostle Paul because he told converts "the truth,"  Galatians 4:16 . See Foe. Cp. echthra, "enmity."

Vine's Expository Dictionary of OT Words [3]

'Ôyêb ( אוֹיֵב , Strong'S #341), “enemy.” 'Ôyêb has an Ugaritic cognate. It appears about 282 times in biblical Hebrew and in all periods. In form, the word is an active infinitive (or more precisely, a verbal noun).

This word means “enemy,” and is used in at least one reference to both individuals and nations: “… In blessing I will bless thee, and in multiplying I will multiply thy seed as the stars of the heaven, and as the sand which is upon the sea shore; and thy seed shall possess the gate of his enemies” (Gen. 22:17—the first occurrence). “Personal foes” may be represented by this word: “If thou meet thine enemy’s ox or his ass going astray, thou shalt surely bring it back to him again” (Exod. 23:4). This idea includes “those who show hostility toward me”: “But mine enemies are lively, and they are strong; and they that hate me wrongfully are multiplied” (Ps. 38:19).

One might be an “enemy” of God: “… The Lord will take vengeance on his adversaries, and he reserveth wrath for his enemies” (Nah. 1:2). God is the “enemy” of all who refuse to submit to His lordship: “But they rebelled, and vexed his holy Spirit: therefore he was turned to be their enemy …” (Isa. 63:10).

Tsâr ( צָר , Strong'S #6862), “adversary; enemy; foe.” This noun occurs 70 times in the Hebrew Old Testament, mainly in the Psalms (26 times) and Lamentations (9 times). The first use of the noun is in Gen. 14:20: “And blessed be the most high God, which hath delivered thine enemies into thy hand.”

Tsâr is a general designation for “enemy.” The “enemy” may be a nation (2 Sam. 24:13) or, more rarely, the “opponent” of an individual (cf. Gen. 14:20; Ps. 3:1). The Lord may also be the “enemy” of His sinful people as His judgment comes upon them (cf. Deut. 32:41-43). Hence, the Book of Lamentations describes God as an “adversary” of His people: “He hath bent his bow like an enemy [ ‘oyeb ]: he stood with his right hand as an adversary [ tsâr ], and slew all that were pleasant to the eye in the tabernacle of the daughter of Zion: he poured out his fury like fire” (Lam. 2:4).

The word tsâr has several synonyms: ’oyeb , “enemy” (cf. Lam. 2:5); sone’ , “hater” (Ps. 44:7); rodep , “persecutor” (Ps. 119:157); ‘arits , “tyrant; oppressor” (Job 6:23).

In the Septuagint, tsâr is generally translated by echthros (“enemy”). The KJV gives these translations: “enemy; adversary; foe.”

Bridgeway Bible Dictionary [4]

Although Christians are to try to live peaceably with everyone ( Romans 12:18), their identification with Jesus Christ means that some will oppose them. Therefore, they will have enemies. The enemies of Christians become the enemies of God, and the enemies of God become the enemies of Christians ( Exodus 23:22;  Psalms 37:20;  Psalms 55:2-3;  Matthew 10:22;  Matthew 10:36). In spite of this, Christians are to love their enemies and do good to those who hate them ( Matthew 5:44;  Luke 6:27;  Romans 12:20; see Hatred ).

The Bible speaks of enemies other than one’s fellow human beings; for example, Satan, death and evil spiritual forces. But Christ has conquered all these through his death and resurrection, and in the day of his final victory he will destroy them for ever ( Matthew 13:39;  Luke 10:18;  1 Corinthians 15:25-28;  Colossians 2:15;  Hebrews 10:12-13).

King James Dictionary [5]

EN'EMY, n. L. inimicus.

1. A foe an adversary. A private enemy is one who hates another and wishes him injury, or attempts to do him injury to gratify his own malice or will. A public enemy or foe, is one who belongs to a nation or party, at war with another.

I way to you, love your enemies.  Matthew 5

Enemies in war in peace friends.

2. One who hates or dislikes as an enemy to truth or falsehood. 3. In theology, and by way of eminence, the enemy is the Devil the archfiend. 4. In military affairs, the opposing army or naval force in war, is called the enemy.

Webster's Dictionary [6]

(1): ( a.) Hostile; inimical.

(2): ( n.) One hostile to another; one who hates, and desires or attempts the injury of, another; a foe; an adversary; as, an enemy of or to a person; an enemy to truth, or to falsehood.

International Standard Bible Encyclopedia [7]

en´e - mi ( איב , 'ōyēbh , צר , car , צר , cār  ; ἐχθρός , echthrós ): "Enemy," "enemies," are frequent words in the Old Testament. The Hebrew word most often so translated is 'ōyēbh , meaning perhaps literally, "one who hates"; very frequent in the Psalms, e.g.  Psalm 3:7;  Psalm 6:10;  Psalm 7:5;  Psalm 8:2;  Psalm 9:3 ,  Psalm 9:1;  Psalm 13:2 , where the cry is often for deliverance from enemies. Another word for "enemy," found chiefly in the poetical books, is cār , or car , "distresser," "straitener" ( Numbers 10:9;  Job 16:9;  Psalm 27:2 ,  Psalm 27:12 , the Revised Version (British and American) "adversary," etc.); also cārar ( Esther 3:10;  Psalm 8:2;  Psalm 10:5 the King James Version, etc.). Other words are ‛ār , "one awake" ( 1 Samuel 28:16 the King James Version;   Daniel 4:19 the King James Version); sānē' , perhaps, "to be sharp or bite" ( Exodus 1:10;  Proverbs 25:21;  Proverbs 27:6 ); shārar , "to watch" ( Psalm 5:8;  Psalm 27:11 ), and ḳūm , "to stand up," or "withstand" ( Exodus 32:25 ).

In the New Testament echthros , "enemy," "opponent," is the only word translated "enemy" ( Matthew 5:43 ,  Matthew 5:14;  Mark 12:36;  Luke 1:71 ,  Luke 1:74 , etc.;  Romans 5:10;  Romans 11:28 , etc.), once with ánthrōpos ("a man"), joined to echthros ( Matthew 13:28 ).

In the Revised Version (British and American) "adversary" is frequently substituted for "enemy" ( Numbers 24:8;  Deuteronomy 32:41;  Psalm 6:7;  Psalm 7:6;  Psalm 44:10 , etc.); for "O thou enemy," etc. ( Psalm 9:6 ) we have "The enemy are come to an end"; instead of "When the enemy shall come in like a flood, the Spirit of the Lord shall lift up a standard against him" ( Isaiah 59:19 ) we have "For he will come as a rushing stream, which the breath of Yahweh driveth" (with the text of the King James Version in margins); for "The fire of thine enemies shall devour them" ( Isaiah 26:11 ), "Fire shall devour thine adversaries" (text of the King James Version in the margin).

The frequent reference to enemies in the Old Testament is what we should expect to see in these early times on the part of a people settling in a land that had been occupied by other tribes, worshipping other gods. The spirit of their law was that expressed by our Lord in His Sermon on the Mount, "Thou shalt love thy neighbor, and hate thine enemy." This He changed: "but I say unto you, Love your enemies." An approach toward this spirit had been made in the later prophets by their inclusion of the whole world under one God, who had a gracious purpose toward all, but the near statement of it we only find in  Proverbs 25:21 (quoted by Paul,   Romans 12:20 ). See also  Exodus 23:4 , and compare  2 Kings 6:22;  2 Chronicles 28:15 .