kabad -- to be honored, to be great, to be plentiful, to be glorious, to multiply oneself, to make oneself numerous
The basic meaning of adding honor to father and mother is giving them grandchildren, in obedience to the Urgebot to be fruitful and multiply, and in fulfillment of the promise to Abraham to make his descendants as the sands of the seashore and the stars of the firmament. It's not simply about "obedience", as Luther would have it in his Large Catechism. Few commentators, in fact, connect the honoring of parents with the number of their posterity as the Old Testament does generally.
Children's children are the crown of old men; and the glory of children are their fathers.
-- Proverbs 17:6
Lo, children are an heritage of the LORD: and the fruit of the womb is his reward. As arrows are in the hand of a mighty man; so are children of the youth. Happy is the man that hath his quiver full of them: they shall not be ashamed, but they shall speak with the enemies in the gate.
-- Psalm 127:3ff.
That in blessing I will bless thee, and in multiplying I will multiply thy seed as the stars of the heaven, and as the sand which is upon the sea shore; and thy seed shall possess the gate of his enemies;