nitpicker
nit·pic·ker
noun
1.
someone who makes small and unjustified criticisms
Origin
From nitpick + -er.
Related words
Word family
Broader terms
WordNet 2.1 (Princeton University). Wiktionary (CC BY-SA). WordNet 2.1 Copyright Princeton University. All rights reserved. Wiktionary content is available under the Creative Commons Attribution-ShareAlike Licence.