Longman Dictionary of Contemporary English
Douglas Harper's Etymology Dictionary
Wiktionary
n. (context idiomatic English) the act of finding exceedingly small differences which are probably neither important nor noticeable to most people.
Usage examples of "hair-splitting".
As a piece of hair-splitting it was brilliant, and reconciled many in the Senate to Pompey who were obdurately against a proconsular command going to a man outside the Senate.
Any questioning of the judges, quibbling, hair-splitting, or whining could yield a heavy fine, strippage, ejection, or all three.
And it could also explain why all of the cults, regardless of their superficial bickerings and hair-splittings, are united in calling for JEVEX to be restored.
Never would he have dared to present either of them to the Duchess, conscious instinctively of the air with which she would have listened to Brichot's monologues and Elstir's hair-splittings, the Guermantes spirit regarding pretentious and prolix speech, whether in a serious or a farcical vein, as alike of the most intolerable imbecility.