noun.
A poultice or plaster, spread over one's skin as medical treatment.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
noun.
a medical dressing consisting of a soft heated mass of meal or clay that is spread on a cloth and applied to the skin to treat inflamed areas or improve circulation etc.
Word Usage
"The clay cataplasm (that the vet authorized!) is working, along with the antibiotics."