What is "allomerism"

Allomerism \Al*lom"er*ism\, n. [Gr. ? other + ? part.] (Chem.) Variability in chemical constitution without variation in crystalline form.

n. (context chemistry English) variability in chemical composition without variation in crystalline form.

n. (chemistry) variability in chemical composition without variation in crystalline form

Allomerism is the similarity in the crystalline structure of substances of different chemical composition.