Definitions for nigglingˈnɪg lɪŋ
Random House Webster's College Dictionary
petty; trivial; inconsequential.
demanding too much care, attention, time, etc.
Origin of niggling:
fiddling, footling, lilliputian, little, niggling, piddling, piffling, petty, picayune, trivial(adj)
(informal) small and of little importance
"a fiddling sum of money"; "a footling gesture"; "our worries are lilliputian compared with those of countries that are at war"; "a little (or small) matter"; "a dispute over niggling details"; "limited to petty enterprises"; "piffling efforts"; "giving a police officer a free meal may be against the law, but it seems to be a picayune infraction"