WordWeb Online

1. A technical system of symbols used to represent special things
   - notational system
    
2. A comment or instruction (usually added)
   "he added a short notation to the address on the envelope";
   - note, annotation
    
3. The activity of representing something by a special system of marks or characters

Derived forms: notations

Type of: comment, commentary, committal to writing, writing

Encyclopedia: Notation