To fall or drop into water with a soft sound; or to set something down heavily or carelessly.
Imitative word—it sounds like the action it describes. Onomatopoeia that emerged in the 17th century in English, meant to replicate the sound of something hitting water.
Onomatopoeia like 'plop,' 'splash,' and 'fizz' are actually more sophisticated than they sound—different languages use different sounds for the same actions because they perceive and value different acoustic details.
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