Definitions for niggly
Random House Webster's College Dictionary
nig•gleˈnɪg əl(v.i.)-gled, -gling.
(n.)to spend too much time and effort on inconsequential details; trifle.
to criticize in a peevish way; carp.
Origin of niggle:
1610–20; < Scand; (ult. < ON hnøggr stingy, c. OE hnēaw); cf. niggard
bad-tempered, especially about trivial details.
pernickety, paying too much attention to small details.