The word separate has a variety of antonyms that describe different aspects of being joined or combined. One antonym for separate is "unite," which refers to bringing together multiple things into a whole. Another antonym is "attach," which means to connect or fix one thing to another. Conversely, "disconnect" is the antonym that describes the act of separating something that was previously connected. "Merge" is another antonym, meaning to combine or blend things so that they become one. Finally, "integrate" refers to the process of combining different pieces into one cohesive whole, creating a more complex system. Together, these antonyms highlight the different ways in which things can come together or be pulled apart.