Out of period
Out Of Period (often abbreviated OOP) refers to anything that was not discovered or in general use during the time-frame accepted to be covered by the SCA. By contrast, anything that falls within the accepted time-frame is said to be "in period" or simply period.
Some items that would technically be OOP are considered "in period by consensus" (not sure of the exact phrasing) as life would be way too difficult without them. Some examples include: