The phrase "time on one's hand" refers to having a lot of free time, but there are several antonyms that describe the opposite. The first antonym is "busy," which means being actively engaged in work or other activities, leaving little or no free time. People who are busy often struggle to find time for leisure activities. The second antonym is "occupied," meaning someone who is fully engaged in a task or project and has no free time to spare. Another antonym is "occupied," which means being physically or mentally engaged in something, leaving no time for leisure activities. Lastly, "hectic" is another antonym which means being in a state of constant activity, making it difficult to find time for relaxation.