fallback

fallback — noun

IPA/ˈfɔːlbæk/
KK[fˈɔlbˌæk]IPA/ˈfɔːlbæk/

1. another option you have prepared in advance so that you can use it if your main

1.nounB2
Definition

another option you have prepared in advance so that you can use it if your main plan does not work or something you depend on suddenly becomes unavailable.

Example

Padma always packs a power bank as a fallback in case her phone dies during fieldwork.

as a fallback in case [X]

If the new supplier is late again, the factory will use last year's vendor as a fallback.

use [X] as a fallback

Common collocations
  • a fallback plan
  • a fallback option
  • a fallback position
  • have a fallback
  • use as a fallback
Synonyms
  • backup

    more everyday; very common in tech contexts

  • contingency

    more formal; emphasises planning for risk

  • reserve

    broader; often used for resources, not plans

Antonyms
  • main plan

    the primary choice you intend to use first

Grammar Patterns

a fallback (for/in case of X)

have a fallback

Usage Note

Often appears as 'as a fallback' or 'have a fallback' — speakers stress that the option is held in reserve, not used by default.

Common Mistakes

I will use the fallback first.
I will keep the second option as a fallback.
a fallback is the reserve choice, not the first choice.

fallback — adjective

IPA/ˈfɔːl.bæk/
KK[fˈɔlbˌæk]IPA/ˈfɑːl.bæk/

fallback — verb

Word family

Synonym discussion

Sense: noun/1

All five words name a non-primary option, but they part ways on tone and framing. 'Fallback' and 'backup' are everyday neutral words for a reserve choice; 'backup' is the most common in tech and casual speech ('keep a backup of your files'), while 'fallback' often carries the sense of switching to it only after the first plan visibly fails. 'Contingency' is more formal and corporate, and it usually pairs with 'plan' ('a contingency plan for natural disasters') — it stresses risk planning rather than a single ready choice. 'Alternative' is the widest of the five and does not imply reserve status: an alternative may be chosen first. 'Plan B' is informal and chatty, often spoken: 'I always have a Plan B in case the date is boring.'

fallback ↗backup ↗contingency ↗alternative ↗plan B

Common collocations

Nouns

Phrases

  • have a fallback
  • use as a fallback
  • keep something as a fallback

Prepositions

  • as a fallback
  • in case (of)

Etymology

Old EnglishMiddle EnglishModern English

Formed in the 19th century from the English phrasal verb 'fall back' (Old English 'feallan' + 'bæc'), meaning to retreat or move backwards. Over time, the joined noun and adjective form 'fallback' shifted from this military sense of retreat to its modern meaning of a reserve option that is ready when the first choice fails.