泵

Bottom 水 in its full form - the indexing radical and the substance being moved. The character is read top-to-bottom as 'stone on water' = a mechanical pump driving liquid. Unlike most water-radical characters that use the side-form 氵, 泵 keeps full 水 underneath because the character is built to picture water trapped below a weight, with the four-stroke wave-pattern flowing out the sides.

Top 石 - pictograph of a chunk of stone fallen from a cliff (厂 cliff + 口 fragment). Here it sits on top to picture weight pressing down. 泵 is a modern compound ideograph for the English loanword 'pump': stone weight bearing on water = water forced out under pressure. A rare invented Chinese character for a Western mechanical concept.