PLURALS OF LATIN NOUNS USED IN ENGLISH

First Declension

Nouns ending in -a, plural in -ae

alumna [foster daughter], pl. alumnae

ala [wing], pl. alae

 

Second Declension

Nouns ending in -us, plural in -i

alumnus [foster son], pl. alumni

locus [place], pl. loci

Nouns ending in -um, plural in -a

datum [thing given], pl. data

medium [middle], pl. media

Third Declension

Examples:

onus [n. burden], base oner-, plural onera

appendix [fem. an addition], base appendic-, plural appendices

Plurals: a) masculine and feminine, base + -es

index [forefinger, pointer], base indic-, pl. indices

cicatrix [scar > "scar tissue"], base cicatric-, pl. cicatrices

b) neuter, base + -a

genus [kind, birth], base gener-, pl. genera

corpus [body], base corpor-, pl. corpora

Fourth Declension

Nouns end in -us. The Latin plural is spelled the same as the singular.

hiatus [gap], pl. hiatuses (or hiatus)

plexus [network], pl. plexuses (or plexus)

nexus [bond], pl. nexuses (or nexus)

Fifth Declension

Nouns in -es; the plural is the same as the singular.

species [appearance > kind], pl. species

caries [decay] pl. caries