English

Noun

actinost ‎(plural actinosts)

1. (ichthyology) A bone at the base of a paired fin (of a fish)
   • 1889, Dr. G. Baur, Journal of morphology, Volume 3‎, On the morphology of ribs and the fate of the actinosts of the median fin in fishes:

     The second well-developed actinost is below the vertebra supporting the subcaudal blood-vessels, but that is not so strong proximally as the first; the ribs are not directed downwards, but backwards, and are entirely separated from each other.