a plural ending of nouns borrowed from Greek and Latin: phenomena; criteria; data; errata; genera.
Dictionary.com Unabridged
-a
2
a feminine singular ending of nouns borrowed from Latin and Greek, also used in Neo-Latin coinages to Latinize bases of any origin, and as a Latin substitute for the feminine ending -ē of Greek words: anabaena; cinchona; pachysandra.
-a
3
an ending of personal names forming feminines from masculines: Georgia; Roberta.
Origin: < L feminine -a (see -a2), as Claudia, feminine of Claudius
-a
4
a suffix designating the oxide of the chemical element denoted by the stem: alumina; ceria; thoria.
Origin: probably generalized from the -a of magnesia
