Question

A break or open sore in the surface of the skin membrane which does not heal quickly

Answer 1

Hy,
Breach in the continuity of epithelium of skin is an ulcer.
Macule is a flat lesion
Papule is an elevated lesion
Pustule is a lesion filled with pus
Hope it helps.
Regards
Dr Chinmay
Thanks

Answer 2

All those wounds that do not heal in some time take the shape of ulcers.

"Ulcer is an open sore on external or internal surface of the body, range from a small sore in the mouth to chronic sore in the stomach and intestine."

There are multiple reasons that a wound doesn't heal quickly; such as poor blood circulation, fluid build-up and constant re-occurrence of infection.