blue pencil
/ˈbluːˌpɛnsəl/
verb
- To edit, correct, or censor written material, especially by marking it with a blue pencil.
- The editor had to blue-pencil several paragraphs to meet the word limit.
- The government agency blue-penciled sensitive information from the report before releasing it.
- The teacher blue-penciled the student's essay for grammar mistakes.