What does adiamorphic mean?
Solution 1:
Diamorphic is defined as "Existing or occurring in two distinct forms; exhibiting dimorphism." by the OED, its etymology being: Greek δίμορϕος of two forms ( < δι-, δίς twice + μορϕή form) + -ic suffix.
So I would hazard a wild guess at adiamorphic meaning "not of two forms", and further suggest that it implies being of one form only.