Fall down and Fold up

Fall down verb - Lose an upright position suddenly.

Fold up and fall down are semantically related in collapse inward topic. In some cases you can use "Fold up" instead a verb "Fall down".

Fold up verb - Bend or lay so that one part covers the other.

Fall down and fold up are semantically related in collapse inward topic. Sometimes you can use "Fall down" instead a verb "Fold up".