Here's what rhymes with dimorphism.

Consider these alternatives

coloration / operation plumage / unit colouration / relation predation / operation variability / stability diurnal / internal variation / relation morphological / logical genders / members morphology / quality beak / seek phenotype / might copulation / population polymorphism / dwarfism reactivity / activity cannibalism / given objectification / education vocalization / organization pigmentation / operation seasonality / personality carapace / made