Part of speech:
To object when there is little reason to do so; resort to trivial faultfinding; carp; quibble (at or about)
A trivial matter or minor concern raised in arguing or finding fault.
To render subtle:
Find another word for split-hairs. In this page you can discover 9 synonyms, antonyms, idiomatic expressions, and related words for split-hairs, like: chop-logic, cavil, make a fine distinction, nitpick, pick nits, quibble, refine a distinction, sharpen a distinction and subtilize.