Sit-up and Sit up

Sit-up noun - A stomach exercise in which a person sits up from a supine position without using the arms for leverage.

Sit up and sit-up are semantically related. In some cases you can use "Sit up" instead a verb phrase "Sit-up".

Sit up verb - Change to an upright sitting position.

Sit-up and sit up are semantically related. Sometimes you can replace phrase "Sit-up" with "Sit up", this terms are similar.