Archaic KJV Word
Fruit
Modern equivalent: results
What Was Lost
The diagnostic function. 'By their fruits ye shall know them' was not 'judge people by their results' but 'the visible product of a life reveals the invisible root.' Fruit was diagnostic -- it told you what kind of tree you were dealing with. The fruit of the Spirit was the evidence that God's Spirit was the root of your life.
Closest Survivor in Modern English
fruit (still used metaphorically but the 'reveals true nature' dimension needs emphasis)
Peak Usage (1611)
KJV Genesis 1:11 -- 'Fruit tree yielding fruit after his kind'; Galatians 5:22 -- 'The fruit of the Spirit'
Died still used but produce-ified (~1800)
Hebrew peri ('the natural, visible product of a living thing/the evidence of what something truly is') reduced to 'food from trees.' The organic, evidence-bearing, identity-revealing dimension was lost to the grocery aisle.
What Replaced It
“produce”
Agricultural commodity; fruit was the visible evidence of invisible root character
“results”
Mechanical output; fruit was the natural, organic outgrowth of what something truly was
“outcome”
End product; fruit was ongoing evidence of the life-source -- bad trees cannot bear good fruit