“Sub” is a Latin prefix meaning “beneath.” A subordinate is an individual who is lower in rank than someone else. A subway is a transport system that’s underground. A submarine travels below the surface of the water. A subcompact is a car that is even smaller than a compact car. You get the idea.
In the case of a subordinate clause, writers are dealing with a group of words that don’t quite have the status of a full sentence. While these groups of words have a subject and a verb – the two key components of any clause or sentence – they also begin with a subordinate conjunction that reduces their power.
Let me illustrate.
- The price of oil has gone up.
- If the price of oil has gone up…
In the first example, The price of oil has gone up has all the ingredients of a full sentence. The subject is the price of oil, and the verb, or predicate, is has gone up. The structure can stand on its own. It’s a complete idea.
On the other hand, in the second example, there’s a sense of incompletion. Yes, oil prices might have risen, the thought is there, but the subordinate conjunction if signals that there’s more at stake here. What the reader needs to know is what happens if the price of oil has gone up. And there could be any number of answers:
- If the price of oil has gone up, gasoline is going to get even more expensive.
- If the price of oil has gone up, there will be more reason to use alternate sources of energy.
- My financial position will improve if the price of oil has gone up.
- Environmentalists will be pleased if the price of oil has gone up.
In each of these cases, the idea of rising oil prices has been subordinated. It’s no longer the primary focus of the sentence. Instead, other ideas take primary place:
- Gasoline is going to get even more expensive.
- There will be more reason to use alternate sources of energy.
- My financial position will improve.
- Environmentalists will be pleased.
You might have noticed one quirk of punctuation in these examples. When the subordinate clause comes first, it is followed by a comma. But there is no comma when it comes after the main clause.
The opening comma shows that the subordinate clause is only introductory material: the comma signals the reader that the most important idea is coming up. But because the subordinate clause is still important to the meaning of the whole sentence, it should never be cut off by a comma when it’s placed at the end.