Sure, you can use some synonym, or at the very least give a definition. But like I was saying earlier, you don’t want to just avoid using the most proper terms just because the audience might not be familiar with them. If you always avoid using words or talking about things that people don’t know about, how exactly are people supposed to learn? Don’t be afraid to pull people into new things. Sure you want to pay attention and make sure that they are following and keeping up with you, but that doesn’t mean you can’t lead them anywhere.
So sure, define what you mean, but I would still use the term at least once. More than half of education is just exposure. Work this down to the right length: “This means a decrease in the interest rate results in an increase in the present value of capital goods—and of course by ‘capital goods’ we mean ‘produced factors of production’; stuff that is made, just for the purpose of making other stuff. Like a hammer, or a fishing net, or backhoe. Those are ‘capital goods’.”
In situations like this you really want to stay away from using nebulous terms like “capital” because there are so many ways that word is defined it will only confuse things. Not to mention, there is a difference between “capital” and “capital goods”. Just because many people incorrectly use a word, doesn’t mean you should keep doing it just because you think it might help them understand.
If you really want to get into it, here’s a list of resources for details on “capital” and “capital goods”