Interesting words, issue two

There are a lot of words to get through. Here is the second set of five. It took me a while to think of a suitable way to number these posts. "Volume" is traditionally used to indicate the year in periodical publications, so didn't quite fit for these: they would all be part of volume one for the first year. In the interest of brevity, I decided to just call these individual posts issues. Coming up with good example sentences is also a bit more difficult than I expected. 

choropleth: (and bonus word, a related term: isochrone. These words describe types of maps) Greek etymology. A type of map where different colors are used to show data regarding specific areas. A map depicting vaccination rates by postal code would be a choropleth map. Isochrone maps show travel times from a given location. A map showing walkshed times and distances could be an isochrone map. 

oneiric: resembling or pertaining to dreams. Greek etymology. I did not learn this one in my Greek and Latin roots vocabulary workbook from fourth or fifth grade. Each time I remember a dream, I record it in an oneiric notebook for future reference. Oneiric subject matter often includes some elements from waking life.

iatrogenic: Greek etymology. A medical term. It describes a disease, injury or other adverse outcome induced by the words or actions of the physician or by medical treatment or diagnostic procedure. An iatrogenic effect of chemotherapy is hair loss. The vaccine may cause temporary iatrogenic side effects like muscle pains and headaches. 

palimpsest: Greek/Latin etymology. There are a variety of different definitions depending on the context, but these are the few that are of particular interest to me. a) A manuscript or document that has been erased or scraped clean, for reuse of the paper, parchment, vellum, or other medium on which it was written. b) (cultural studies) The partial erasure of or superimposition on an older society or culture by a newer one. c) [broadly] Something bearing the traces of an earlier, erased form. Upcycled envelopes are a palimpsest of the paper bags they are made from. The building is a palimpsest of its former existence as a motel. 

aposematism: Greek etymology again. Primarily a zoological term. It means an adaptation, especially (but not limited to) a form of coloration, that warns off potential predators. The thorns on a wild blackberry plant are a form of aposematism.