יָסַף yâçaph (H3254)

to add or augment (often adverbial, to continue to do a thing)

1) to add, increase, do again 1a) (Qal) to add, increase, do again 1b) (Niphal) 1b1) to join, join oneself to 1b2) to be joined, be added to 1c) (Hiphil) 1c1) to cause to add, increase 1c2) to do more, do again

a primitive root;