oneeyedjohn:chomping is correct, wtf did champing come from
sorry - the expression is "champing at the bit".
Chomping comes from people who did not understand 'champing' - and keep saying it wrongly and eventually enough people get it wrong that it starts to become accepted.
like:- it all goes well instead of it augers well
it's a mute point instead of a moot point
one foul swoop instead of one fell swoop
Both chomping and champing mean to 'chew noisily' - but chomping is part of the process of eating - while champing implies not eating - just chewing. As horses generally are not 'eating' the bit, champing is the correct term. A horse can 'champ' without anything in its mouth -- you cannot 'chomp' on nothing. This is the difference between 'chomping' the transitive verb, and 'champing' the intransitive verb - ie no object required to be champed on.
But trying to justify the correct term grammatically is not really the key issue. 'Champing at the bit' has been used for centuries. Just because relatively recently, a lot of people say it incorrectly - does not make the 'new' version correct.