reconsideration vs second thought

reconsideration and second thought both are nouns.

Word	Noun	Adjective	Verb	Adverb
reconsideration	Yes	No	No	No
second thought	Yes	No	No	No

As nouns, reconsideration and second thought are synonyms defined as:

reconsideration and second thought: thinking again about a choice previously made

Other synonyms of reconsideration include afterthought, rethink.

reconsideration (noun)	second thought (noun)
thinking again about a choice previously made	thinking again about a choice previously made
a consideration of a topic (as in a meeting) with a view to changing an earlier decision