grammar - If an independent clause stands on its own, is it still considered a clause?

There are several definitions related to clauses in my textbook that am a little confused about, and I would greatly appreciate some clarification.

Here are the definitions:

1. Clause. A group of words which contains a subject and a verb but is in itself not a complete sentence, but a part of a complex or compound sentence.




2. A complex sentence is a sentence which contains at least one dependent and one independent clause.

   
   
   

   
   

   While we were away, our house was robbed.

   
   




3. An independent clause is a main clause, one that is not subordinate.

In the example given in definition 2, we have a dependent clause ("While we were away") and an independent clause ("our house was robbed.") It seems to me that the independent clause can stand on its own as a sentence ("Our house was robbed.")

However, it looks like based on definition 1, this would not qualify as a clause, since it is itself a complete sentence and is not part of a complex or compound sentence.

Is it correct to say that when an independent clause stands on its own, it is not considered a clause? If so, is it considered anything besides "a sentence"?

Thanks!