WordNet sense 1 (the state of something that has been unused and neglected):

disuse

WordNet sense 2 (lack of attention and due care):

disregard

WordNet sense 3 (the trait of neglecting responsibilities and lacking concern):

neglectfulness, negligence

WordNet sense 4 (fail to do something; leave something undone):

fail

WordNet sense 5 (failure to act with the prudence that a reasonable person would exercise under the same circumstances):

carelessness, nonperformance

WordNet sense 6 (give little or no attention to):

ignore

WordNet sense 7 (leave undone or leave out):

drop, miss, omit, overlook, overleap, pretermit, overlook, leave out