The crossword solution for the term 'MORE THAN A PLOP' is THUD, which is a four letter word. THUD is an onomatopoeia, which is a word that imitates or suggests the source of the sound that it describes. It is usually used to describe a dull, heavy sound, such as the sound of a heavy object hitting the ground. In this case, it is used to describe something that is more than just a plop, which is a light, soft sound.