"Called it a day" is an idiomatic expression that means to stop working or doing an activity for the day. The opposite of this phrase is "working around the clock," which means to work continuously without stopping. Similarly, "continuing the task" or "resuming the activity" are antonyms for "called it a day." Another antonym for this phrase is "delaying the work," which means not completing the task on time or procrastinating. In contrast, "finishing the work" or "completing the task" are synonyms for "called it a day." These antonyms highlight the contrast between stopping work and continuing to work without breaks.