The antonyms for the phrase "after consideration" could be words like hasty, impulsive, careless, reckless, thoughtless, or rash. These terms imply a lack of forethought or consideration before taking any action or decision. On the other hand, synonyms for "after consideration" include deliberate, thoughtful, intentional, planned, and careful. These words suggest that one has taken enough time to think and evaluate before making any decision. Therefore, it is essential to consider antonyms of a term in addition to its synonyms to understand its full range of meanings and contexts. Ultimately, the choice of words reflects the quality of communication and the thought process behind it.