Backup

Alternative forms

 * back-up

Noun

 * 1) A reserve or substitute.
 * If the goalkeeper is injured, we have a backup.
 * 1)  A copy of a file or record, stored separately from the original, that can be used to recover the original if it is destroyed or damaged.
 * After the power failure, we had to restore the database from backup.
 * 1) An accumulation of material that halts the flow or movement of something.
 * The blockage caused a backup in the plumbing.
 * 1)  reinforcements
 * He's got a gun - you better send for backup.

Synonyms

 * (reserve): reserve, stand-in, spare, substitute
 * (computing: copy of a file or record):
 * (accumulation of material that halts flow): block, blockage

Adjective

 * 1) standby, reserve or extra
 * I am only a backup player.
 * 1)  That is intended as a backup.
 * Make a backup copy of that file.

Synonyms

 * (reserve): extra, reserve, spare, standby

Thesaurus
about-face, about-turn, advocate, agent, alter ego, alternate, alternative, amicus curiae, analogy, attorney, back track, back trail, backing, backing off, backing out, backing up, backup man, champion, change, changeling, comparison, copy, counterfeit, deputy, double, dummy, equal, equivalent, ersatz, exchange, executive officer, exponent, fake, figurehead, fill-in, ghost, ghostwriter, imitation, lieutenant, locum, locum tenens, makeshift, metaphor, metonymy, mock, next best thing, paranymph, personnel, phony, pinch, pinch hitter, pleader, procurator, provisional, proxy, relief, replacement, representative, reserve, reserves, reversal, reverse, reversing, reversion, right-about, right-about-face, ringer, second in command, second string, secondary, sign, spare, spares, stand-in, stopgap, sub, substituent, substitute, substitution, succedaneum, superseder, supplanter, surrogate, swingaround, symbol, synecdoche, temporary, tentative, third string, token, turnabout, turnaround, understudy, utility, utility man, utility player, vicar, vicar general, vicarious, vice, vice-president, vice-regent, vicegerent, volte-face