I also guess that some people prefer using mean squared deviation as a name for variance because it is more descriptive -- you instantly know from the name what someone is talking about, while for understanding what variance is you need to know at least elementary statistics. Check the following threads to learn more:
The meaning of LEAST is lowest in importance or position. How to use least in a sentence.
adjective the superlative of little' that can be used with mass nouns and is usually preceded by the'; a quantifier meaning smallest in amount or extent or degree “didn't care the least bit” “he has the least talent of anyone” see more adverb used to form the superlative
least meaning, definition, what is least: less than anything or anyone else: Learn more.
LEAST definition: 1. less than anything or anyone else; the smallest amount or number: 2. less than anything or…. Learn more.
- smallest in size, amount, degree, etc.; slightest: to pay the least amount of attention. 2. lowest in consideration, position, or importance.
You use least to indicate that something is true or happens to a smaller degree or extent than anything else or at any other time. He had a way of throwing her off guard with his charm when she least expected it.
least (plural leasts) Preceded by the: superlative form of little: most little; the lowest - ranking or most insignificant person or (sometimes) group of people.
least /list/ adj., [a superlative of] little with less or lesser as comparative. lowest in amount: wasn't paying the least attention. something that is least: Your little problem is the least of my worries right now. [superl. of] little with less as compar. to the smallest extent, amount, or degree: That's the least important question of all.