Learn English – A “human cue tip”

The word mortal is used to describe people in contrast to immortals, beings that cannot die, such as gods or similar entities in works of fiction or myth. You wouldn’t use the word mortal to refer to humans in any context except one where humans were being either implicitly or explicitly compared to gods.

The book title Running for Mortals is kind of a joke, implying that unlike other books containing advice and instruction for runners that are only applicable to those with godlike ability, stamina, and discipline, this book can be used by mere mortals.

Bummock is the bottom part of the berg and Hummock is the top part.

Here is a good link I found that explains better. I know I saw something on National Geographic channel a few years ago with the names and drought (sp?) measures the bummock.

Now FumbleFingers makes a few points about bummock. Well he is right, kind of. It has various definitions. I don't disagree that one of them is "broken ice under the hummock, forced downward by pressure". What he is describing is a description for an iceberg. Also bummock seems the industry standard (oceanography) to describe the submerged part of froze ice which the user was asking for. As noted in my link above and Susan's link it means the bottom of an iceberg.

As for the use of keel I find it was lazily used in a couple articles. It refers to the bottom of a "boat". In the same articles they referred to the top as a "sail". I think it was more for analogy purposes than giving it an actually name. For sure joe-average-reader wouldn't understand the bummock usage. So I won't say that keel is wrong but it's just a descriptor not the word. We can use the sail/keel analogy for anything floating in any body of water and there is no specificity to icebergs.