niggling

Adjective

 * 1) Petty
 * 2) * 1863, Charles Darwin's letter to J. D. Hooker, 14th of July 1863
 * My dear Hooker, I am getting very much amused by my tendrils, it is just the sort of niggling work which suits me, and takes up no time and rather rests me whilst writing.
 * 1) Irritating.

Noun

 * 1) A small irritating sensation.