It goes back to the times when we evolved as humans. Frankly speaking, the fact is that initially there was no language; no words and people only used body language and symbolic gestures to communicate with each other. Gradually language came into picture and along with it came words.
Now as modern and developed human beings, we can safely and surely say that we think in words. The more words we have in our vocabulary, the more ideas we can have. This conditioning of our minds is due to the way we were taught words since our childhood. For every action or thought, we have a word associated with, and thus when we are thinking, we have a dialog of words running in the background. In today’s world we are surrounded with words and thus it’s difficult for us to think without them.
Although some people will argue with the reasoning that how does a deaf person thinks since a person who is deaf since birth do not have any word in his or her vocabulary. This reasoning is correct in its own aspect and we can safely say that they are exceptions. Since they do not have words or have only limited number of words, they can only think to a certain extent and not beyond that.
A research was conducted on a community, which spoke the language that had no words for numbers. It was found that they could differentiate between one, some and many, but if they were given to choose from exact number of objects such as between sixteen and seventeen, they failed. This proved that words are necessary to have a clear picture of the situation at hand.
So the next time when you come across a word that you are not aware of, then the best way to tackle this situation is to find its meaning earliest possible since the more words you know, the better you can think.