the GNU version of the Collaborative International Dictionary of English
adj. Marked by a relapse; falling back; tending to return to a former worse state.
The Century Dictionary and Cyclopedia
Sliding or falling back; marked by a relapse or return to a former worse state.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. a failure to maintain a higher state
Word Usage
"There are different types of -- that we call the relapsing remitting then the secondary progressive where there is an ongoing weakness or a progression of symptoms."