Introduction
Third Declension i-Stem Nouns
The third declension contains a group of nouns called i-stems.
There are two subcategories of i-stem nouns: pure and mixed.
Pure i-Stem Nouns
Pure i-stem nouns include nouns of feminine and neuter gender.
They follow the parisyllabic rule, meaning they have the same number of syllables in the nominative singular and genitive singular.
Mixed i-Stem Nouns
Mixed i-stem nouns are identified by the double consonant rule.
They include nouns of all three genders (masculine, feminine, and neuter).
Latin Feminine i-Stem Nouns
In medicine, there is a small group of Latin feminine i-stem nouns with limited use.
Examples include:
ravis, is, f - hoarseness
sitis, is, f - thirst
febris, is, f - fever, temperature, pyrexia
febris continua - continued fever
febris curativa - artificial pyrexia
febris flava - yellow fever (jack), black vomit
febris Q - Queensland fever
tussis, is, f - cough
pertussis, is, f - whooping cough
pelvis, is, f - id.
pelvis ossa coxae = os sacrum + os coccygis
pelvis renalis - kidney's pelvis
pelvis angusta - contracted pelvis
pelvis plana - flat pelvis
Greek Feminine i-Stem Nouns
In medicine, there is a large group of Greek feminine i-stem nouns.
These nouns denote a state, condition, or process of degeneration and destruction.
They have been Latinized and adapted to the feminine i-stem declension.
The Latin ending -is can be replaced by the ending -e in English.
Example: dosis, is, f - dose
Greek Neuter i-Stem Nouns
Greek neuter i-stem nouns end in -e, -al, and -ar in the nominative singular.
They have the characteristic nominative/accusative plural ending -ia.