"cartilaginous cavity in the upper windpipe where vocal sounds are made," 1570s, from French larynx (16c.), via medical Latin, from Greek larynx (genitive laryngos) "the upper windpipe," which is probably from laimos "throat" (a word of uncertain etymology) but influenced by pharynx "throat, windpipe" (see pharynx).
word-forming element in medicine denoting "diseases characterized by inflammation" (of the specified part), Modern Latin, from Greek -itis, feminine of adjectival suffix -ites "pertaining to." Feminine because it was used with an implied nosos "disease," a feminine noun; especially in arthritis (nosos) "(disease) of the joints." Arthritis (16c.) was one of the earliest appearances of the suffix in English and from it the suffix was abstracted in other uses.
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Definitions of laryngitis from WordNet
inflammation of the mucous membrane of the larynx; characterized by hoarseness or loss of voice and coughing;