Longest word in Spanish

This article describes some of the longest words in the Spanish language.
"Esternocleidooccipitomastoideos" (31-letters) is the plural of the noun "esternocleidooccipitomastoideo", which is the sternocleidomastoid, a muscle in the human neck. The word has a 22-letter synonym: "esternocleidomastoideo", which is shorter because it omits the Latin prefix "occipito-" (occipital). Both words are abbreviated as "ECOM".
The 24-letter word "electroencefalografistas", plural of "electroencefalografista", means "electroencephalographists" or "electroencephalographers": specialists in the brain measurement technology of electroencephalography (EEG).
The 23-letter adverb "anticonstitucionalmente" means "anticonstitutionally". "Anticonstitucionalmente" is also the Portuguese translation; the French translation, "anticonstitutionnellement", is an exceptionally long word as well (25 letters).
Long words.
In the table below, all of the Spanish nouns except for "arteriosclerosis" can be pluralised by adding an "s" ("es" for internacionalizaciones) to the end. The adjective "otorrinolaringológico" can also be pluralised with an "s"; the plurals of the other adjectives end in "es".
The "RAE" column indicates whether the Real Academia Española lists and defines the word in the "Diccionario de la lengua española", its official dictionary.