pumps is a form of:

Convolution



noun
1.
ចង្វាយ, ភ្នែន
ENGLISH MEANING
noun
1.
The act of rolling anything upon itself, or one thing upon another; a winding motion.
2.
The state of being rolled upon itself, or rolled or doubled together; a tortuous or sinuous winding or fold, as of something rolled or folded upon itself.
3.
An irregular, tortuous folding of an organ or part; as, the convolutions of the intestines; the cerebral convolutions.