Lewis & Short

1. vŏpiscus, i, m., one of a pair of twins, born alive after the premature birth and death of the other: vopiscos appellabant a geminis, qui retenti utero nascerentur, altero interempto abortu, Plin. 7, 10, 8, § 47; Non. p. 557, 3; Sol. 1 med.; Isid. Orig. 9, 5.