-ia (Greek > Latin: a suffix that forms nouns; state of, condition of, quality of; act of).

Names of countries; such as, Australia, Tasmania, et al. Manchuria,

Names of diseases; such as, hydrophobia, mania, hyperalgia, hysteria, et al. pneumonia,

Names of chemical alkaloids; such as, aconitia, atropia, conia, morphia, et al. strychinia,

Names of flowers from the names of the discoverer or the person who introduced the flower; such as, Dahlia, Wisteria, Fuschsia, et al. zinnia,

Names of classes and orders in botany and zoology; such as, Mammalia, Reptilia, Amphibia, et al. Zinnia,

Names of collective nouns; such as, academia, militaria, suburbia Names of things relating to something; such as, pedodontia, orthodontia, psychedelia, telesthesia, et al. Plurals of Latin and Greek nouns that end with -um; such as, paraphernalia, regalia, saturnalia, et al.