Misc: In the world of communications for what do the letters U R L stand for?

Questions

A health profession concerned with the prevention, diagnosis, & treatment of disorders of the teeth & adjacent tissues of the head, neck, & mouth?

A heavy winter fog containing ice crystals is a _____?

A hippo can open its mouth wide enough to fit a 4 foot tall ______?

A horse's hoof is also known by what grim term?

A hot spring which shoots steam into the air is a _______?