intransitive verb
object for no good reason: to make objections about something on small and unimportant points
noun
carping criticism: a trivial and unreasonable objection
[Mid-16th century. Via French caviller< Latin cavillari< cavilla "mockery"]
http://encarta.msn.com/encnet/features/dictionary/DictionaryResults.aspx?refid=1861595612
to make unreasonable complaints, especially about things that are not important
"The one cavil I have about the book is that it is written as a diary."
http://dictionary.cambridge.org/define.asp?key=12067&dict=CALD
—v.i.
to raise irritating and trivial objections; find fault with unnecessarily (usually fol. by at or about): He finds something to cavil at in everything I say.
—v.t.
to oppose by inconsequential, frivolous, or sham objections: to cavil each item of a proposed agenda.
—n.
1. a trivial and annoying objection.
2. the raising of such objections.
http://dictionary.infoplease.com/cavil
http://en.wiktionary.org/wiki/cavil?rdfrom=Cavil&redirect=no