Strong’s Greek
G2670 — katapontizo
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
καταποντίζω
katapontizo — pronounced kat-ap-on-tid'-zo
from 2596 and a derivative of the same as 4195; to plunge down, i.e. submerge:--drown, sink. see GREEK for 2596 see GREEK for 4195
2 occurrences in the KJV.
Matthew 14:30
But when he saw the wind boisterous, he was afraid; and beginning to sink, he cried, saying, Lord, save me.
Matthew 18:6
But whoso shall offend one of these little ones which believe in me, it were better for him that a millstone were hanged about his neck, and that he were drowned in the depth of the sea.