backstop (n.) Look up backstop at Dictionary.com
1819, "something at the back as a barrier;" see back (adj.) + stop (n.). In U.S. baseball, from 1889, "fence a short distance behind the catcher;" figurative extension to "catcher on a baseball team" is from 1890. The verb is attested from 1956 in the sense of "support." Related: Backstopped; backstopping.