古フランス語のmot, comment, remark, epigramから、ラテン語のmuttire, mumble, mutter, onomatopoeiaから、語源的にはmotet, mutterから。
The mot juste is an expression which readers would like to buy of writers who use it, as one buys one's neighbour's bantam cock for the sake of hearing its voice no more. [Fowler]