Synonyms for Failed:

adj.

abortive (adjective)
fruitless, unproductive, useless, failing, ineffectual, vain, unsuccessful, futile.
bankrupt (adjective)
lost.
failed (adjective)
Flunked, Flopped, collapsed, fallen.
failing (adjective)
unsuccessful.
insolvent (adjective)
busted.
unsuccessful (adjective)
counterproductive, abortive, disastrous, botched, foiled, unproductive, thwarted, unsuccessful, futile, useless, in vain, bungled, frustrated, fruitless, vain, ineffectual, pointless.

n.

failed (noun)
failing, unsuccessful.

v.

failed (verb)
fallen, Faltered, Blundered, Floundered, lost, Stumbled, collapsed, busted, Flunked, fell, Flopped.
neglected (verb)
forgotten, Forgot, ignored, disregarded, neglected, overlooked.

Other synonyms:

Other relevant words:
bungled, failing, botched.

Usage examples for failed

  1. If I ever tried to get through a door and failed it might not be pleasant for me. – Laramie Holds the Range by Frank H. Spearman
  2. " You can only half will," he would say to people who failed – Self Help by Samuel Smiles
  3. Suddenly his voice failed him. – The Captain of the Kansas by Louis Tracy