A person who cavils; a faultfinder, quibbler or nitpicker

Of a person, having achieved success by one's own efforts, with little to no support from family members and others. / Of a thing, made by oneself instead of bought or taken over.

The process of descending a fixed rope in a standing position while facing the ground.

(genetics) A sequence of bases (in a nucleic acid) that is absent in one species (especially human) but may be present in others.