I am not much of a dictionary maker, but I believe I could improve upon either and say, 'An obiter dictum is the passing opinion of a Judge expressed when it is not called for.'
I believe that obiter dicta , like the proverbial chickens of destiny, come home to roost sooner or later in a very uncomfortable way to the Judges who have uttered them, and are a great source of embarrassment in future cases.
This mere obiter opinion ought not to weigh against the settled direct authority of the cases which have been deliberately and upon argument determined the other way.
There are 166 volumes of Massachusetts reports, 165 volumes of United States Supreme Court reports, and hundreds and thousands of reports of other States. Every year adds to the reports of the Courts of this country about 250 volumes and about sixty volumes of text-books. 'Words, words, words.' Ben Butler to the contrary notwithstanding, all of these words are law unless they have been pronounced obiter dicta .