Archaic KJV Word
Yoke
Modern equivalent: burden
What Was Lost
The partnership. A yoke bound two animals together so they could pull as one. A young ox was yoked to an experienced one to learn. 'Take my yoke upon you' meant 'bind yourself to me and we will pull together -- I will take the heavy side.' Jesus was not offering a burden but a partnership where He bore the greater weight.
Closest Survivor in Modern English
yoke (still used in 'unequally yoked' but the partnership and shared-labor image is lost)
Peak Usage (1611)
KJV Matthew 11:29-30 -- 'Take my yoke upon you, and learn of me...For my yoke is easy, and my burden is light'
Died still used but obsoleted (~1900)
Hebrew ol and Greek zygos ('yoke/the wooden beam binding two animals for shared work/the coupling device for partnership') became obsolete as agriculture mechanized. The partnership and shared-labor imagery vanished.
What Replaced It
“burden”
Weight to endure; a yoke was a partnership device -- two working together
“obligation”
Duty imposed; a yoke connected you to a partner who shared the load
“oppression”
Negative; Jesus's yoke was specifically 'easy' because He pulled alongside you