In our modern religious culture prayer is a communication between man and God. While this definition could be applied to some passage of the Bible (such as Genesis 20:17) it is not an Hebraic definition of the Hebrew word palal. By looking at the etymology of this word we can better see the Hebraic meaning. The word palal comes from the parent root pal meaning "fall" (The root pal is most likely the root of our word fall which can etymologically be written as phal). Pal is also the root of the Hebrew word naphal also meaning "fall". The word palal literally means to "fall down to the ground in the presence of one in authority pleading a cause". This can be seen in Isaiah 45:14 where the Sabeans fall down and make supplication (this is the Hebrew word palal) to Cyrus.
AHLB# 1380-B (V)