Accustomed to refers to something that has become habitual or familiar over time. It can be challenging to find the perfect synonym for this phrase, but some alternatives include used to, well-versed in, familiar with, accustomed, habituated, and acclimatized. These words all imply a level of experience with something, whether it's a task, a situation, or a particular routine. When searching for the right word, consider the context and tone of your writing, as well as the audience you're addressing. With a little creativity and care, you can find the perfect synonym to convey your intended meaning.