Webster’s Revised Unabridged Dictionary · 1913
Plop
Plop, v. i. [imp. & p. p. Plopped; p. pr. & vb. n. Plopping.] [Imitative.] To fall, drop, or move in any way, with a sudden splash or slap, as on the surface of water.
The body plopped up, turning on its side. Kipling.
Plop, n. Act of plopping; the sound made in plopping.