1. The subordination that occurs when a conjunction makes one linguistic unit a constituent of another
   "In 'Because it was raining, we stayed home', 'because' is a subordinating conjunction"
    
2. A conjunction (like 'since' or 'that' or 'who') that introduces a dependent clause
   "In the sentence 'I'll go if you go,' 'if' is a subordinating conjunction";
   - subordinate conjunction

Derived forms: subordinating conjunctions

Type of: conjunction, conjunctive, connective, continuative

Encyclopedia: Subordinating conjunction