If you tread on something, you put your foot on it when you are walking or standing.

If you tread in a particular way, you walk that way.

A person's tread is the sound that they make with their feet as they walk.

If you tread carefully, you behave in a careful or cautious way.

The tread of a step or stair is its flat upper surface.

The tread of a tyre or shoe is the pattern of thin lines cut into its surface that stops it slipping.

If someone is treading a fine line or path, they are acting carefully because they have to avoid making a serious mistake, especially in a situation where they have to deal with two opposing demands.

If you tread a particular path, you take a particular course of action or do something in a particular way.

If someone who is in deep water treads water, they float in an upright position by moving their legs slightly.

If you say that someone is treading water, you mean that they are in an unsatisfactory situation where they are not progressing, but are just continuing doing the same things.