Archaic KJV Word
Kingdom
Modern equivalent: territory/realm
What Was Lost
The active reign. 'Thy kingdom come' was not 'take us to heaven' but 'let your reign break into earth now -- let your will be done here as it is there.' The kingdom was not a place to go but a reality to enter and live under. When Jesus said 'the kingdom is at hand,' He meant God's reign was arriving in the present moment.
Closest Survivor in Modern English
kingdom (still used but heard as 'a place' rather than 'God's active reign breaking into the world')
Peak Usage (1611)
KJV Matthew 6:10 -- 'Thy kingdom come'; Mark 1:15 -- 'The kingdom of God is at hand'
Died still used but spatialized (~1800)
Hebrew malkut and Greek basileia ('reign/rule/active exercise of kingly authority') were spatialized into 'a place with borders.' The kingdom of God became a territory you go to rather than a reign you live under.
What Replaced It
“realm”
Geographical territory; basileia was primarily about the king's active rule, not a map location
“domain”
Area of control; kingdom meant the dynamic, active, expanding reign of the king
“heaven”
Afterlife destination; 'the kingdom is at hand' meant God's reign was breaking into the present