Archaic KJV Word
Worship
Modern equivalent: praise
What Was Lost
The concept of declaring ultimate worth. To worship was to make a public valuation: this being is worth everything. The word carried economic and social weight -- you were assigning supreme worth to God above all competitors. Modern 'worship' often means little more than singing with eyes closed.
Closest Survivor in Modern English
worship (still used but mostly associated with music rather than life-encompassing worth-declaration)
Peak Usage (1611)
KJV John 4:24 -- 'God is a Spirit: and they that worship him must worship him in spirit and in truth'
Died still used but hollowed (~1970)
Reduced from worth-ship (Old English weorthscipe, 'declaring the worth of') to 'religious activity,' particularly singing in church services.
What Replaced It
“praise”
One component of worship; worth-ship encompassed all acts that declared God's supreme value
“church service”
A time slot rather than a posture of the soul
“singing”
One expression of worship mistaken for its entirety