What does "subordinating conjunction" mean?

A word that appears at the beginning of a subordinate clause and establishes its nature.

Subordinating conjunction

Common synonyms include: adjective, adverb, clause connector, conjunction, conjunction, connecting word.

noun

noun ·Rare ·Advanced level

Noun

1
A word that appears at the beginning of a subordinate clause and establishes its nature.
"Near-synonym: subordinator"
2
a conjunction (like ‘since’ or ‘that’ or ‘who’) that introduces a dependent clause wordnet
3
the subordination that occurs when a conjunction makes one linguistic unit a constituent of another wordnet