A blot is a stain or spot that damages something's appearance. An ink blot on a white shirt, a blot of mud on clean carpet, or a blot on someone's reputation are all marks that stand out and draw attention. In this sense, people sometimes say that a mistake or scandal is “a blot on their record,” meaning it's a blemish that damages how others see them.

As a verb, to blot means to soak up or dab away liquid, usually with something absorbent. Blotting paper is special absorbent paper designed specifically for soaking up excess ink or liquid. Before modern pens, people used blotting paper constantly to dry wet ink on letters and documents. Scientists still use blotting paper in laboratories to absorb liquids in experiments.