offspring are all produced in a single group (litter, clutch, etc.)and then the parent usually dies.

offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.

ability to breed only once during lifetime, the organism dies shortly after breeding

Salmon that are able to spawn only once during their lifetime.

organisms that reproduce only once, usually followed by death.