- Noun pluralization suffix; sometimes with vocalic ablaut in the pluralized noun
- forms nouns denoting where something or someone is from; -ian
- forms adjectives indicating relation to; -ian
- Used to form country names; -ia
From Latin -ia (neuter plural). In some cases, analysable within German as a regular plural of an earlier form in -ium; e.g. Principium as an obsolete variant of Prinzip. The singular ending was sometimes lost, leaving -ien as a new, irregular plural suffix. In other cases, simply following the Latin i-declension (singular in -e, plural in -ia).
- Used to form the plurals of some neuter nouns of Latin descent whose original plural ends in -ia.
- Not all nouns whose Latin plural is -ia necessarily take this ending. Some take a regular plural in -e, or have both forms alongside (for example, Reptile).
-ien (feminine equivalent -ienne)