subordinate conjunction
Definition - (Aka subordinator | subordinating conjunction | subordinating connective)

A conjunction that introduces a subordinate clause.
Note: Some examples are although, before, until, while, because, and if.

Example -
Because we were bored, we decided to go to the movies.

In the above, prefixing the subordinate conjunction because to the clause we were bored, turns it into a subordinate clause.

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