Since becoming an editor almost 30 years ago, I've enjoyed studying word usage. Why do we use one word over another?
Most of the time, we use similar words interchangeably, even though they each may have distinct meanings. Unfortunately, we sometimes use the wrong word. In my opinion, this is because we're not actually taught to talk; we just pick up our native language and begin using words we've heard in certain contexts many times over. If we hear two different words used in the same context, we may assign them the same meaning. When we become students of words, we want to differentiate similar words and their meanings.
If the difference is subtle, the misuse may go unnoticed -- such as using acquire rather than obtain. However, sometimes the use is glaring -- such as using literally instead of figuratively.
Which brings me to preventive and preventative. I have usually held the opinion that the word preventative does not exist. When the word popped up in manuscripts, and I would always change it to preventive. It just seemed silly to add an extra syllable to a word.
Then my daughter, Sally, chimed in with the same gripe, so I began a little research. Now, word usage and definitions are subjective, but I concluded that preventive should be used as an adjective, and preventative should be used as a noun. For example, "Changing your car's oil regularly is an effective means of preventive maintenance." Or, "Inoculations are an effective preventative against disease." In the first case, preventive modifies the noun maintenance. In the second, preventative is the noun itself.
I should probably share what I learned about my initial examples: obtain and acquire, and literally and figuratively. From my limited research, I reached the conclusion that obtain means to take possession of something deliberately, whereas acquire means to take possession whether intentional or not. If you buy a shirt at a second-hand store, you have obtained the shirt. But if there happens to be a $20 bill in the pocket of the shirt, you have acquired $20. Interestingly, most PR people announce that their company has acquired a smaller company. This implies that the acquisition was purely a stroke of luck, rather than the result of long and careful consideration.
I am always amused when someone misapplies the word literally -- especially if they are a communications professional, and, hence, should know better. I still remember an entertainment critic writing, "Her performance was so captivating, she literally held the audience in the palm of her hand." Either this performer had one huge hand, or her audience was composed of ants. Obviously, the writer meant to use figuratively. To me, when someone misapplies the word literally, it makes them sound like they're trying to appear smarter than they are by using big words they don't know the meaning of.
So when I am speaking of people who possess something, and I don't know if they obtained it deliberately or if it just fell into their lap, I will say that they "obtained, acquired, or otherwise took possession of" the item. I know. It's annoying, but sometimes I like to be annoying.