The correct spelling is "flattest" (D), which means most level or having the least thickness.
The abyssal plains are flat or very gently sloping areas of the deep ocean floor. They are among the Earth's flattest and smoothest regions and the least explored. Abyssal plains generally lie between the foot of a continental rise (shelf) and a mid-oceanic ridge.
aeronautical sleeping
precambian
The Precambrian Era is the longest era with the least amount of scientific information available. This is because so few fossils have been discovered.
The least expensive mode of transportation is by water. It is fuel efficient, less polluting and the safest. It is also the least expensive to move cargo.
In the US at least, women do.
he has admitted to sleeping with at least 10 other women.
The longest factor string is 2x2x2x3x13. It is always best to list your factor string from the least to greatest number.
Sleeping uses the least amount of energy, as the body is at rest and functions are minimized during this time.
unprosperousness
eating, sleeping, drinking and last but not least farting