[adjective] [before noun; not gradable]A fallback plan or position is one which can be used if other plans do not succeed or other things are not available.We must have a fallback position in the negotiations.Their first choice for the job is Amanda Martin, with Paul Davies as the fallback. [before noun]
FALLBACK
Meaning of FALLBACK in English
Cambridge English vocab. Кембриджский английский словарь. 2012