Antonyms for the phrase "in a jiffy" can be "delayed," "slowly," "gradually," "indefinitely," and "procrastinating." These words imply a lack of urgency or immediacy, instead emphasizing a lengthier process. "Delayed" emphasizes a period of waiting before something can occur, while "slowly" and "gradually" imply a leisurely pace. "Indefinitely" suggests a lack of a set timeline, and "procrastinating" implies the deliberate avoidance of tasks. These antonyms stand in contrast to the immediacy and urgency implied by the phrase "in a jiffy," depicting a slower, more cautious approach to completing tasks.