We were not at home when our friends arrived.

conjunctive adverb

coordinating conjunction

correlative conjunction

subordinating conjunction

Subordinating Conjunction

Explanation:

In the sentence, "We were not home when our friends arrived," the subordinating conjunction is "when."

Subordinating Conjunction - This refers to a word or phrase that connects a dependent clause to an independent clause. This conjunction is located in the subordinate clause, which is also known as dependent clause. It is easy to tell whether a clause is dependent because it doesn't tell a complete idea.

Examples of subordinating conjunctions: until, unless, till, so that, since, provided, if, how, even though, as if, as long as, as soon as, etc.

Going back to the example sentence above, the subordinating conjunction is "when," while the subordinate clause is "when our friends arrive." Notice that the subordinate clause cannot be understood completely if removed from the sentence.