Comfortably means in a way that feels physically pleasant and relaxed, or with enough resources that you don't have to worry or strain. When you sit comfortably in a chair, your body feels at ease without any awkward positions or tension. When you live comfortably, you have enough money for your needs and some wants, though not necessarily enough to be wealthy.

The word suggests having more than the bare minimum. A family living comfortably can pay their bills without constant stress, take an occasional vacation, and handle unexpected expenses like car repairs without panic. A student who finishes a test comfortably within the time limit has plenty of minutes to spare and can check their work carefully.

You can also use comfortably to describe doing something easily or confidently. A runner who comfortably wins a race has energy left over and never seems in danger of losing. A musician who plays comfortably at a fast tempo isn't struggling to keep up.