Basic Guidelines For English Spellings
READ THESE ARTICLES
1Forming nouns adopted unchanged from Latin or Greek (such as mania, militia), and modern Latin terms (such as utopia).
2Medicine
Forming names of states and disorders.
3Forming names of countries.
Representing Latin or Greek endings.
1Forming noun plurals from Greek neuter nouns ending in -ion or from those in Latin ending in -ium or -e.
2Zoology
Forming noun plurals in the names of classes.