Meaning of second thought

sec'ond thought'

Pronunciation: [key]
  1. Often,reservation about a previous action, position, decision, judgment, or the like: He had second thoughts about his decision.
  2. after reconsideration: On second thought, I don't think I'll go.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.