Over at the Log, Mark Liberman quotes a spiky and suggestive short story by D. Barthelme, “They Called for More Structure.” He does so in the context of an analogy to syntax in machine translation that is neither comprehensible nor interesting to me; what is interesting to me is the punchline of the story, where the workers “saw the new city spread out beneath us, in the shape of the word FASTIGIUM. Not the name of the city, they told us, simply a set of letters selected for the elegance of the script.” Huh, I thought, I studied Latin and I don’t remember the word fastigium. So I looked it up in my handy paperback dictionary and found this farrago of senses: “gable; pediment; roof, ceiling; slope; height, elevation, top, edge; depth, depression; finish, completion; rank, dignity; main point, heading, highlight (of story, etc.).” This is how you can tell if you really like a language: if I were dealing with a Greek or Russian word, I would be pleased at the complex semantics, but since it’s Latin I just groan and think “Does any language really need a word like that?” (The first i is long, by the way, and apparently there is no clear etymology.)
It’s been borrowed into English (per the OED in an entry first published in 1895 and not updated since) in the senses “The apex or summit; spec. in Archit. the ridge of a house,” “The gable end (of a roof); a pediment,” and “The acme or highest state of intensity (of a disease)”; the last is the only sense given in the AHD.