Longman Dictionary of Contemporary English - plop

~1 n a sound like something solid dropping into liquid  (The soap fell into the bath with a loud plop.) ~2 v plopped, plopping 1 to fall somewhere making a sound like a plop + on/down etc  (A few drops of rain began to plop on to the roof.) 2 to put something into a liquid so that it makes a sound like a plop + into  (I plopped a couple of ice cubes into the drink.) 3 plop (yourself) down to sit down or lie down heavily  (She plopped down on a chair.)