meantime

The meantime is the stretch of time between two events. What happens while you are waiting for the main thing.

It almost never stands alone, and lives in the phrases in the meantime and for the meantime. In the meantime is far the commoner, and it means while that is being sorted out. Meanwhile does the same job as a single adverb and is more flexible, so most writers use that instead. The word is one word, and it comes from mean in its old sense of middle.