correction fluid 
noun [mass noun]
An opaque liquid painted over a typed or written error so as to allow for the insertion of the correct character.Oven cleaner, model glue, spray paint, correction fluid, paint thinner, and polyurethane are just a few of the household products that are dangerous....
- Males were marked with a little green spot of typists' correction fluid to allow for identification.
- Females were marked with a single dot of white correction fluid so that we could easily identify the sex of individuals within mating pairs.