Partial Knock-Out

A Partial Knock-Out is Vanilla option that ceases to exist if the Knock-Out level is reached within a predetermined period during the life of the option, i.e., the possibility of the option being knocked-out is confined to a "sub-period" only, not the whole maturity period.

This may also before be referred to as a WIndow Knock-Out, where the barrier is observed during a "start" and "end" window period.