Rules for forming Greek and Latin Plural Nouns

when a greek singulr noun ends in -is

form the plural by changing -is to -ides

when a greek singulr noun ends in -nx

form the plural by changing -nx to -nges

when a greek singulr noun ends in -oma

form the plural by changing -oma to -omata

when a greek singulr noun ends in -on

form the plural by changing -on to -a

when a latin singulr noun ends in -a

form the plural by changing -a to -ae

when a latin singulr noun ends in -us

form the plural by changing -us to -i

when a latin singulr noun ends in -um

form the plural by changing -um to -a

when a latin singulr noun ends in -is

form the plural by changing -is to -es

when a latin singulr noun ends in -ex

form the plural by changing -ex to -ices

prefix

an optional word beginning

combining form

the foundation of a medical word

suffix

a word ending