Strong’s Greek
G2086 — heterozugeo
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
ἑτεροζυγέω
heterozugeo — pronounced het-er-od-zoog-eh'-o
from a compound of 2087 and 2218; to yoke up differently, i.e. (figuratively) to associate discordantly:--unequally yoke together with. see GREEK for 2087 see GREEK for 2218
1 occurrence in the KJV.
2 Corinthians 6:14
Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness?