rider
[noun]
Synonyms: appendix, addendum, codicil, supplement

[TahlilGaran] English Synonym Dictionary ▲

rid‧er /ˈraɪdə $ -ər/ noun [countable]
[Word Family: noun: ride, rider, riding, override; verb: ride, override; adjective: overriding]

1. someone who rides a horse, bicycle etc ⇒ cyclist:
a horse and rider

2. an extra or more detailed piece of information that is added to an official document and changes it slightly

[TahlilGaran] Dictionary of Contemporary English ▲