unequally yoke together with

Boyd’s Bible Dictionary:

(join). This well-known means of coupling oxen for agricultural purposes was primitively laid upon the necks of the cattle, and held there by thongs which passed around their necks. A thong served also as an attachment to the cart-tongue or plow-beam. A pair of oxen yoked together were called a yoke, as today (1 Sam. 11:77And he took a yoke of oxen, and hewed them in pieces, and sent them throughout all the coasts of Israel by the hands of messengers, saying, Whosoever cometh not forth after Saul and after Samuel, so shall it be done unto his oxen. And the fear of the Lord fell on the people, and they came out with one consent. (1 Samuel 11:7); 1 Kings 19:2121And he returned back from him, and took a yoke of oxen, and slew them, and boiled their flesh with the instruments of the oxen, and gave unto the people, and they did eat. Then he arose, and went after Elijah, and ministered unto him. (1 Kings 19:21)). It would seem as if asses and mules went by pairs like oxen (Judg. 19:1010But the man would not tarry that night, but he rose up and departed, and came over against Jebus, which is Jerusalem; and there were with him two asses saddled, his concubine also was with him. (Judges 19:10); 2 Kings 5:1717And Naaman said, Shall there not then, I pray thee, be given to thy servant two mules' burden of earth? for thy servant will henceforth offer neither burnt offering nor sacrifice unto other gods, but unto the Lord. (2 Kings 5:17)), and even horses, camels, and chariots (Isa. 21:77And he saw a chariot with a couple of horsemen, a chariot of asses, and a chariot of camels; and he hearkened diligently with much heed: (Isaiah 21:7)). The word, like the Latin jugum, gave rise to a measurement of land (1 Sam. 14:1414And that first slaughter, which Jonathan and his armorbearer made, was about twenty men, within as it were an half acre of land, which a yoke of oxen might plow. (1 Samuel 14:14)), the amount a yoke of oxen could plow in a day. Yoke is used metaphorically for subjection (1 Kings 12:4,9-114Thy father made our yoke grievous: now therefore make thou the grievous service of thy father, and his heavy yoke which he put upon us, lighter, and we will serve thee. (1 Kings 12:4)
9And he said unto them, What counsel give ye that we may answer this people, who have spoken to me, saying, Make the yoke which thy father did put upon us lighter? 10And the young men that were grown up with him spake unto him, saying, Thus shalt thou speak unto this people that spake unto thee, saying, Thy father made our yoke heavy, but make thou it lighter unto us; thus shalt thou say unto them, My little finger shall be thicker than my father's loins. 11And now whereas my father did lade you with a heavy yoke, I will add to your yoke: my father hath chastised you with whips, but I will chastise you with scorpions. (1 Kings 12:9‑11)
; Isa. 9:44For thou hast broken the yoke of his burden, and the staff of his shoulder, the rod of his oppressor, as in the day of Midian. (Isaiah 9:4); Jer. 5:55I will get me unto the great men, and will speak unto them; for they have known the way of the Lord, and the judgment of their God: but these have altogether broken the yoke, and burst the bonds. (Jeremiah 5:5)). An unusually heavy bondage was typed by “iron yoke” (Deut. 28:4848Therefore shalt thou serve thine enemies which the Lord shall send against thee, in hunger, and in thirst, and in nakedness, and in want of all things: and he shall put a yoke of iron upon thy neck, until he have destroyed thee. (Deuteronomy 28:48); Jer. 28:1313Go and tell Hananiah, saying, Thus saith the Lord; Thou hast broken the yokes of wood; but thou shalt make for them yokes of iron. (Jeremiah 28:13)). Removal of the yoke implied deliverance (Gen. 27:4040And by thy sword shalt thou live, and shalt serve thy brother; and it shall come to pass when thou shalt have the dominion, that thou shalt break his yoke from off thy neck. (Genesis 27:40); Jer. 2:2020For of old time I have broken thy yoke, and burst thy bands; and thou saidst, I will not transgress; when upon every high hill and under every green tree thou wanderest, playing the harlot. (Jeremiah 2:20); Matt. 11:29-3029Take my yoke upon you, and learn of me; for I am meek and lowly in heart: and ye shall find rest unto your souls. 30For my yoke is easy, and my burden is light. (Matthew 11:29‑30)). Breaking of the yoke meant repudiation of authority (Nah. 1:1313For now will I break his yoke from off thee, and will burst thy bonds in sunder. (Nahum 1:13)).
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Concise Bible Dictionary:

Women plowing near Hebron. Dec. 8, 1937
The harness that secures an animal to a cart or plow; and the beam to which two animals are fastened for any purpose of labor; it is also used to denote the number two, as “a yoke of oxen” (1 Sam. 11:77And he took a yoke of oxen, and hewed them in pieces, and sent them throughout all the coasts of Israel by the hands of messengers, saying, Whosoever cometh not forth after Saul and after Samuel, so shall it be done unto his oxen. And the fear of the Lord fell on the people, and they came out with one consent. (1 Samuel 11:7)). It is employed as a symbol of servitude and slavery (Jer. 28:2-142Thus speaketh the Lord of hosts, the God of Israel, saying, I have broken the yoke of the king of Babylon. 3Within two full years will I bring again into this place all the vessels of the Lord's house, that Nebuchadnezzar king of Babylon took away from this place, and carried them to Babylon: 4And I will bring again to this place Jeconiah the son of Jehoiakim king of Judah, with all the captives of Judah, that went into Babylon, saith the Lord: for I will break the yoke of the king of Babylon. 5Then the prophet Jeremiah said unto the prophet Hananiah in the presence of the priests, and in the presence of all the people that stood in the house of the Lord, 6Even the prophet Jeremiah said, Amen: the Lord do so: the Lord perform thy words which thou hast prophesied, to bring again the vessels of the Lord's house, and all that is carried away captive, from Babylon into this place. 7Nevertheless hear thou now this word that I speak in thine ears, and in the ears of all the people; 8The prophets that have been before me and before thee of old prophesied both against many countries, and against great kingdoms, of war, and of evil, and of pestilence. 9The prophet which prophesieth of peace, when the word of the prophet shall come to pass, then shall the prophet be known, that the Lord hath truly sent him. 10Then Hananiah the prophet took the yoke from off the prophet Jeremiah's neck, and brake it. 11And Hananiah spake in the presence of all the people, saying, Thus saith the Lord; Even so will I break the yoke of Nebuchadnezzar king of Babylon from the neck of all nations within the space of two full years. And the prophet Jeremiah went his way. 12Then the word of the Lord came unto Jeremiah the prophet, after that Hananiah the prophet had broken the yoke from off the neck of the prophet Jeremiah, saying, 13Go and tell Hananiah, saying, Thus saith the Lord; Thou hast broken the yokes of wood; but thou shalt make for them yokes of iron. 14For thus saith the Lord of hosts, the God of Israel; I have put a yoke of iron upon the neck of all these nations, that they may serve Nebuchadnezzar king of Babylon; and they shall serve him: and I have given him the beasts of the field also. (Jeremiah 28:2‑14); 1 Tim. 6:11Let as many servants as are under the yoke count their own masters worthy of all honor, that the name of God and his doctrine be not blasphemed. (1 Timothy 6:1)). Also of the grievous bondage of being under the law (Acts 15:1010Now therefore why tempt ye God, to put a yoke upon the neck of the disciples, which neither our fathers nor we were able to bear? (Acts 15:10); Gal. 5:11Stand fast therefore in the liberty wherewith Christ hath made us free, and be not entangled again with the yoke of bondage. (Galatians 5:1)). The Lord Jesus invites the believer to take His yoke upon him, and to learn of Him; that is, giving up self-will, to be in submission to the will of God, content to be in the lowest place; and such will find rest to their souls. His yoke is easy, and His burden is light (Matt. 11:29-3029Take my yoke upon you, and learn of me; for I am meek and lowly in heart: and ye shall find rest unto your souls. 30For my yoke is easy, and my burden is light. (Matthew 11:29‑30)).
Courtesy of BibleTruthPublishers.com. Most likely this text has not been proofread. Any suggestions for spelling or punctuation corrections would be warmly received. Please email them to: BTPmail@bibletruthpublishers.com.

Strong’s Dictionary of Greek Words:

Greek:
ἑτεροζυγέω
Transliteration:
heterozugeo
Phonic:
het-er-od-zoog-eh’-o
Meaning:
from a compound of 2087 and 2218; to yoke up differently, i.e. (figuratively) to associate discordantly
KJV Usage:
unequally yoke together with