Merely / just (而已)

而已 (éryǐ) is a "… and nothing more" that’s a bit more written than 罢了, with which it’s nearly interchangeable. 这只是一个开始而已 = "this is merely a beginning". Like 罢了, it usually leans on 只是/不过. It scales what’s said down to "just that, no more, no less".