Originally Posted by
TheShaman
^ Imo those are slant rhymes. If they had the same endings, i.e., mad pill and cad grill or can grin and man pin, it would just be actual rhymes. What matters are the vowel sounds, more or less exclusively.
In your other example you had bitches senseless > sister wretches > fifth dimension. What would you call fifth dimension if not a slant rhyme? The second syllable is actually closer to the vowel sound of "bit-CHES" in "fifth DI" than in "sis-TER", whereas the last syllable is closer in "wret-CHES" than in "men-SION".
There are no hard definitions of this stuff, as far as I know. So it's just a matter of degree. Mad pill and can grin is a bit of a stretch, but it's all about the context. And I would define slant rhyme pretty much from vowel sounds alone.