reconsideration vs afterthought

reconsideration and afterthought both are nouns.

Word	Noun	Adjective	Verb	Adverb
reconsideration	Yes	No	No	No
afterthought	Yes	No	No	No

As nouns, reconsideration and afterthought are synonyms defined as:

reconsideration and afterthought: thinking again about a choice previously made

Other synonyms of reconsideration include rethink, second thought.

reconsideration (noun)	afterthought (noun)
thinking again about a choice previously made	an addition that was not included in the original plan
a consideration of a topic (as in a meeting) with a view to changing an earlier decision	thinking again about a choice previously made