from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Oriented vertically, with the head to base and tail to chief, as if positioned for diving.
from The Century Dictionary and Cyclopedia
- In heraldry, being in the attitude of diving or plunging: noting a dolphin or fish when represented with the head down.
From Latin ūrīnāns, present active participle of ūrīnor ("I dive"). (Wiktionary)