What exactly did you mean when you wrote `In vedas it is explained as the person who can read vedas.' Could you provide some details?
The root prefix pra- (thoroughly) and the root word math/manth (churn) are of great antiquity and cognates are found in many Indoeuropean languages. The combination pra-math- in Sanskrit has be rough, harass, or destroy as its main meaning, though the root meaning of violent stirring (picture an ocean) is also visible. It has been used as meaning a horse, an epithet for gods (e.g. Ganesha) and demons, and for mythological characters. Even the female form (long open A at the end) is attested in mythology, and it has also been used for a fruit (Terminalia Chebula) better known in North India as harituki.
The root math, to churn, of course has expanded its original meaning as well: the process of churning milk, and starting a fire by wood turning on wood are actually so similar that in Sanskrit it was perfectly acceptable to churn fire or wood, or, for that matter, the loins for a baby. It alone can also mean rub (as in hands to clean it), to stir up, agitate, afflict, destroy, or mix (e.g. medicine), and, theoretically, any of these meanings can be intensified by the use of pra-.
One should also consider the common metaphor in mythology of churning the existing (like milk and ocean) to separate the good (butter and ambrosia) from the bad (whey and poison).