A barrier to which a barrier option is subject for a period shorter than the option’s term. In other words, the option with a partial barrier (known as a partial barrier option) is only observed for barrier breach in either way or both during part of its life, rather than its entire lifespan. The partial observation period is a restricted time period, during which is the underlying price/ rate or variable is monitored for hits. The monitory period can be right at the commencement of an option’s life, or may start any time later on and continues till its maturity date.

A partial barrier is also known as a window barrier (in which case, the option is called a window barrier option).