'Simple majority' is an unfortunate term, in that it has two closely related meanings that sometimes conflict.
A simple majority may be, simply, a majority, that is, more than half.
However, it is also sometimes used for the single largest block; if votes fall 33%, 40%, and 27%, then 40% would be the simple majority. This is more often referred to as a plurality, to avoid confusion. Those who use this definition of a simple majority would refer to the more-than-half majority as an absolute majority.