Subject: Matrices "conformable"
Who is asking: Parent
It looks to me like "conformable" in this context could only mean that multiplication is possible - i.e. if A is n x k and B is k x m, then the product AB makes sense and so A and B are "comformable for multiplication (in that order)". Hence for your example if A is a 5 x 3 matrix and B is a 3 x 5 matrix then AB and BA are both possible so they are conformable for multiplication in both orders.
As for you example that an 8 x 3 and 8 x 1 are said to conformable, I'm baffled. Could there be an error in his text? Possibly it's a typo of "8 x 8 and 8 x 1" or "1 x 8 and 8 x 3". Do you know what source the asker had for this definition ?Cheers,