Simultaneously is a common word that means "at the same time." Some other synonyms for this word can be used to add variety and depth to your writing. Consider using words like concurrently, contemporaneously, together, in tandem, alongside, or side by side. These words can help to convey the same meaning of things happening at the same time, but can add a different tone or nuance to your writing. For example, if you use the word "concurrently," it might suggest a more formal or technical environment, while "in tandem" might suggest collaboration or cooperation. Explore and experiment with these words to make your writing more dynamic!