From sun and pleroo; to implenish completely, i.e. (of space) to swamp (a boat), or (of time) to accomplish (passive, be complete) -- (fully) come, fill up.
KJV: But as they sailed he fell asleep: and there came down a storm of wind on the lake; and they were filledwith water, and were in jeopardy.
NASB: But as they were sailing along He fell asleep; and a fierce gale of wind descended on the lake, and they began to be swamped and to be in danger.