Half-rise and Sit-up

Sit-up and half-rise are semantically related. In some cases you can replace phrase "Sit-up" with "Half-rise", this phrases are similar.

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

Half-rise and sit-up are semantically related. You can use "Half-rise" instead a verb phrase "Sit-up".