Cleanly means doing something in a smooth, precise way that leaves no mess or confusion behind. When a surgeon makes a cleanly cut incision, the edges are neat and straight, making healing easier. When a karate expert breaks a board cleanly in half, it splits in one perfect motion without splintering or cracking in the wrong places.

The word suggests skill and control. A baseball that's hit cleanly soars in a perfect arc because the bat struck it squarely. A diver who enters the water cleanly makes barely a splash. When you cut paper cleanly with scissors, you get a straight edge instead of a ragged, torn mess.

Cleanly can also describe how completely something happens. If negotiations end cleanly, both sides understand the agreement with no lingering confusion. When a branch breaks cleanly off a tree, it snaps at one point rather than tearing and hanging.

The word relates to “clean” but adds the sense of how something is done, not just the result. You might clean your room thoroughly but do it messily, knocking things over along the way. But if you complete a task cleanly, you've done it with precision and control from start to finish.