-iasis

The form -iasis is a suffix used to denote the names of disease or other nouns of state or process. It is often used in medical terms, especially in pathology.

The form -iasis comes from Greek -íasis, denoting the names of diseases. It is a common misconception that -íasis comes from the verb iâsthai, meaning “to heal,” which is the source of the combining forms -iatry and iatro-. Instead, -iasis is derived from the Greek verb ending -áein (also ân), with the initial –i– used as a connecting vowel, featuring the noun-forming suffix -sis.

One example of a word you may have come across that uses the form -iasis is psoriasis, “a common chronic, inflammatory skin disease characterized by scaly patches.” Psoriasis comes from Greek psōríāsis, which uses the equivalent form of -iasis in that language.

The psor- part of the word comes from Greek psṓra, meaning “itch.” The suffix -iasis roughly translates to “itchy disease.”

What are some words that use the combining form -iasis?

• acariasis (using the equivalent form of -iasis in Latin)
• arseniasis
• lithiasis (using the equivalent form of -iasis in Greek)
• nematodiasis
• nephrolithiasis
• toxocariasis

What are some other forms that -iasis may be commonly confused with?

• -iatrics
• -itis
• -osis

The combining form lith- means “stone.” With this in mind, what is the literal translation of lithiasis?