Why do we use the term "singular" to describe singular simplex? Are there any relations between singular matrix (or singular point)and singular simplex?
3. Being beyond what is ordinary or usual; remarkable.
4. Deviating from the usual or expected; odd. See Synonyms at strange.
and I believe it is the meaning appropriate for "singular simplex". Indeed, whereas in simplicial homology, the objects of interest are actual simplices (the n-dimensional generalisation of a triangle), in singular homology, the objects of interest are merely continuous images of simplices. In particular, these images may be very degenerate (a point for instance) and not resemble a simplex at all. That is, they may deviate from what is expected of something called a simplex.