side note

• sidenote

side note (plural side notes)

1. A note or notation made in a side margin.
2. A minor related mention, made as an aside, or afterthought.

   Synonym: sidebar

   As a side note, I'd like to thank that team for their hard work.

• footnote
• endnote
• headnote

• “side note”, in OneLook Dictionary Search.
• side note, sidenote, aside at the Google Books Ngram Viewer.

• sidetone