nit·pick
[nit-pik]
verb (used without object)
1.
to be excessively concerned with or critical of inconsequential details.
verb (used with object)
2.
to criticize by focusing on inconsequential details.
noun
3.
a carping, petty criticism.
adjective
4.
of, pertaining to, or characteristic of a nitpicker or nitpicking.
Also, nit-pick.

Origin:
1965–70; nit1 + pick1

Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.

nitpick

verb
be overly critical; criticize minor details
WordNet® 3.0, © 2006 by Princeton University.

http://dictionary.reference.com/browse/nitpick

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Note added at 13 мин (2014-03-11 14:02:26 GMT)
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Nitpicking is the act of removing nits (the eggs of lice, generally head lice) from the host's hair. As the nits are cemented to individual hairs, they cannot be removed with most lice combs and, before modern chemical methods were invented, the only options were to shave all the host's hair or to pick them free one by one.

This is a slow and laborious process, as the root of each individual hair must be examined for infestation. It was largely abandoned as modern chemical methods became available; however, as lice populations can and do develop resistance, manual nitpicking is still often necessary.

As nitpicking inherently requires fastidious, meticulous attention to detail, the term has become appropriated to describe the practice of meticulously searching for minor, even trivial errors in detail (often referred to as "nits" as well), and then criticising them (see hypercriticism).
http://en.wikipedia.org/wiki/Nitpicking

as an option
http://www.urbandictionary.com/define.php?term=Semantics
http://www.developsense.com/blog/2013/04/semantics/