Definition of "afterthought"

afterthought¹

/ˈæft.ɚ.θɔt/

noun
plural afterthoughts
1. A reflection after an act; a later or subsequent thought, action, or expedient.
2. Something additional to the original plan or concept.
  Quotations
  For most of the past three decades, the natural world was treated almost as an afterthought by world leaders. If discussed at all, it was with platitudes about the need to save polar bears and tigers.
  2019 August 30, Jonathan Watts, “Amazon fires show world heading for point of no return, says UN”, in The Guardian‎
verb
third-person singular simple present afterthoughts, present participle afterthoughting, simple past and past participle afterthoughted
1. (very rare except in the past tense, possibly nonstandard) To expound as an afterthought.