just for grins, I wrote the help desk at the MPL and asked about the word. here is the (suspicions confirmed) response:
In reply to:


I looked in a number of dictionaries including the Oxford English Dictionary
and I didn't find this word either. We do have a reference copy of "Mrs.
Byrne's Dictionary of Unusual, Obscure, and Preposterous Words" from 1974.
Epicaricacy is defined on page 67 as a noun which means "taking pleasure in
others' misfortune." The Random House Unabridged Dictionary defines
schadenfreude as "satisfaction or pleasure felt at someone else's
misfortune."

In the editor's introduction to Mrs. Byrne's Dictionary, this claim is made:

"Incredible as it may seem, every entry in this book, even the most
ludicrous has been accepted as a formal or legitimate English word by at
least one major dictionary."

At the end of the book there is a bibliography of about 85 sources. The
problem is that a source isn't given for each entry.

I checked our catalog and we do have a few of the sources, but since this is
a dictionary of "unusual, obscure, and preposterous words" "epicaricacy"
might turn out to be very difficult to find. You might have to trust Mrs.
Byrne here.