nychthemeral

alternative nycthemeral · alternative nyctohemeral · alternative nictemeral · alternative nuchthemerinal

1. not comparableRelating to or lasting a nychthemeron (a period of 24 hours).

   Observations on sea-anemones in dimly lighted situations, such as under bridges and so forth, showed that these animals were more or less continuously expanded, but aside from such exceptions it was clear that Metridium in its natural surroundings exhibited a well-marked nychthemeral rhythm.

   1919, George Howard Parker, The Elementary Nervous System, Philadelphia: J. B. Lippincott & Co., →OCLC, page 163