Below are some terms often used incorrectly, with explanations and origins.
Traditionally, to decimate something is to reduce its strength or number by ten percent. Decimation came from the Romans. It was a punishment meted out to rebellious legions. The objective of the punishment was to harshly put down an insurrection within a military unit but to not render that unit ineffective for combat operations.
Decimated does not mean destroyed, wiped-out, eliminated, crushed, ruined, etc. People often use the word “decimated” to describe total destruction, perhaps because they feel it sounds dramatic. According to Oxford Dictionaries the incorrect usage of the term has become so widespread that that they have altered the definition to represent its role in common English. Oxford now accepts “decimated” to mean large scale but not total or absolute destruction.
One could argue that Oxford Dictionaries “lowered the standard” of the word specifically or language in general to accommodate for an undereducated population. Others may suggest that this is simply an example of the language evolving. By that logic, if everybody incorrectly identified a dog to be a cat for long enough, then in twenty years or so, “dog” would vanish from the language and all household pets would be known as “cats.”
Possession is 9/10s of the law.
“Possession is nine-tenths of the law.” This statement is true, but not in the context it is usually used. Often this sentence is used to denote a person is the rightful owner of an object simply because it is in their custody. Just because a person controls something however, does not mean they have a 90% claim of ownership. That possession however is likely to be considered theirs until a person can prove otherwise.
Think about it, if you hired a piece of equipment and placed it in your car, would you suddenly have a 9/10 (90%) right of ownership?
If one wished to be factually accurate though and still use that term it is possible. Roughly nine-tenths of the law deals with matters of property, (The remaining roughly ten percent of law deals with rape, assaults, murders, etc.) if used in that context the speaker would be correct.
When the masses misuse and do not understand their language, and we accommodate that incompetence by altering our dictionaries, we have started on a slippery slope towards accepting idiocy as our linguistic standard.