also: びびたるもん
expression, noun
very small amount; insignificant thing; negligible amount
Used to emphasize that something is extremely small, trivial, or hardly worth considering. Often appears in contexts of comparison or dismissal.
彼の給料は微々たるものだ。
His salary is a very small amount.
その差は微々たるものに過ぎない。
The difference is nothing more than a negligible amount.
微々 (bibi) is a reduplication of 微 (bi, 'minute'), combined with the classical auxiliary verb たり (taru) in its attributive form たる, and the noun もの (mono, 'thing'). The phrase literally means 'a thing that is minute'.