failing

nouns

a flaw or weak point
"he was quick to point out his wife's failings"
is derived from
failure to reach a minimum required performance
"his failing the course led to his disqualification"; "he got two flunks on his report"
is derived from
is derived from
antonym

adjectives

below acceptable in performance
"received failing grades"
is similar to
not giving satisfaction
"shops should take back unsatisfactory goods"; "her performance proved to be unsatisfactory"; "life is becoming increasingly unsatifactory"; "our discussion was very unsatisfactory"