-itis

WordReference Random House Learner's Dictionary of American English © 2026

-itis, suffix. 

1. • -itis is attached to roots to form nouns that refer to an inflammation or disease affecting a certain part of the body:
     appendix + -itis → appendicitis;
     bronchi (= part of the lungs) + -itis → bronchitis.
   • -itis is also used to form nouns made up for a particular occasion to refer to something comparable in a funny way to a disease:
     The teenagers seem to be suffering from telephonitis (= excessive use of the telephone, as if using it were a disease).

WordReference Random House Unabridged Dictionary of American English © 2026

-itis, 

1. a suffix used in pathological terms that denote inflammation of an organ (bronchitis;
   gastritis;
   neuritis) and hence, in extended senses, nouns denoting abnormal states or conditions, excesses, tendencies, obsessions, etc. (telephonitis;
   baseballitis).

• Greek
• Neo-Latin (or Latin) -ītis

Collins Concise English Dictionary © HarperCollins Publishers::

-itis suffix:forming_nouns

1. indicating inflammation of a specified part: tonsillitis
2. indicating a preoccupation with or imaginary condition of illness caused by: computeritis, telephonitis

Etymology: New Latin, from Greek, feminine of -itēs belonging to; see -ite¹