noun 1.an act or instance of falling back.
2.something or someone to turn or return to, especially for help or as an alternative: His teaching experience would be a fallback if the business failed.
adjective 3.Also, fall-back. of or designating something kept in reserve or as an alternative: The negotiators agreed on a fallback position.
Origin:
1750–60, Americanism; noun, adj. use of verb phrase fall back