Definitions and synonyms
Meaning is a moving target.
Words change meaning regularly -- either in a broad sense that we may find in a dictionary, or in a personal sense, where you learn a use of a word that you previously didn't know. You may also learn a subtlety about word use that changes the way you use a word, which is to say, changes what you take to be the meaning of the word.
For example, prior to its adoption as a term related to computer networks, "connection" had a more limited meaning than it currently has. A century ago, there was no such thing as a network connection as we know it; "connection" as we know it now, in computer networking, is an extension of previous use of the word "connection". Similar for "run", "boot", "drive", and so on.
Similarly, some words lose meanings over time. For example, the word "speed" used to also mean prosperity or success. Consider the archaic word "godspeed", which was a way to say "hey, I hope things go your way".
Furthermore, you may learn a new sense of a word that you already use. For example: it was pointed out to me that "if' and "whether" suggest different things. "If" suggests a condition: if it rains, then I will bring an umbrella. "Whether" suggests a choice: I don't know whether I'll bring my blue umbrella or my yellow umbrella. In the latter case, we often substitute "if" for "whether", but this is an imprecise substitution. Sure, much writing doesn't require that level of precision -- it's debatable whether that level of precision is even necessary in this course, or virtually ever -- but the point is that I learned something about the words "if" and "whether". For me, their meanings changed. (And I've been tempted to rewrite a lot of stuff I've written prior to learning this subtlety!)
Related to meaning are synonyms. Perhaps surprisingly, some contest the very existence of synonyms. (Check out this reddit thread, for example.) There are a couple of ways to think about this.
First, there (probably) are no two words that mean exactly the same thing. This follows naturally from the point with which I started: Meaning is a moving target. If you can find two words that mean exactly the same thing, wait ten minutes and they won't.
Second, we need to consider a subtlety in how we understand the notion of "same". Except in mathematical applications, "same" almost never means "exactly the same". For example, I went to a party and my friend Mark was wearing the same shirt. We were, however in different shirts, though they were the same shirt. My friend Karen and I like the same whiskey. Though we drink our drams from different glasses. Usually.
On the other hand, when you and I separately solved the equation 2x = 6, we each calculated x = 3. Those answers are the same in a sense different to shirts and drinks.
Synonyms are like these examples. They're words that mean the same, as in the same shirt not as in the same solution to an equation. A synonym, then, is a word that suggests something strikingly similar to another word. A synonym is not a different word for the exact same sentiment.
As a matter of style, we often look for synonyms when we don't want to repeat the (exact) same word several times. A thesaurus can be invaluable in such a search.
As a matter of substance, we look for synonyms when we feel as though the word we've chosen doesn't convey what we meant to mean. Again, a thesaurus can be invaluable, but the selection of just the right word can be a subtle skill. You improve this skill over time.
There is abstract writing as much as there is abstract painting. Words are representational – not concrete. They can be colour and shape all at once.
Don’t try to say everything. (Compare painting / portrait.) Leave words out – as many as you can. It signals the reader that you’ve left space, and moreover, that you need the reader as much as he needs you. There is nothing in the words but what readers put there, and so the writer must preserve a space for the reader.
In the next activity, your task is to find a new word. Consider the examples here: perhaps you've already learned a new word in this course (I've used a few specialised words on purpose, with this activity in mind), or perhaps you have learned a technical term on the job, or in another course, and so forth. Consider where you hear new words, and how this is different from learning a new word.