Second thoughts are the doubts that one has about a decision they have made or an action they are about to take. There are many synonyms for the phrase "second thoughts" including hesitancy, reservation, qualms, uncertainty, skepticism, apprehension, and doubt. Each of these words highlights a specific aspect of the feeling of second-guessing oneself. Hesitancy refers to a lack of confidence in one's own judgment, while reservation implies holding back or being hesitant to fully commit to a decision. Qualms are feelings of uneasiness or doubt about a decision that has already been made, while uncertainty is a general sense of unsureness about the outcome of an action. Skepticism implies a distrust of the outcome, while apprehension suggests anxiety or fear.