Concept: adverbial subordinator

Definition

[[An adverbial subordinator is a grammatical marker that occurs on a clause and indicates that it is an adverbial clause.]]

Comments

In the earlier literature, adverbial subordinators are generally known as "adverbial subordinating conjunctions" ("adverbial subordinators which are separate words are referred to as subordinating conjunctions by traditional grammar"; Dryer 2005: 382). They may occur as clitics, or as affixes on the verb, and in the latter case they may also be known as "converbal affixes". Here the term "subordinator" is used equally for all such markers, regardless of their affixal or clitic status (note that Kortmann 1997 excluded affixes).

Croft's comparative concept
adverbializer (STR):

adverbializer (STR) = a morpheme that overtly expresses the semantic relation in an adverbial clause construction. Example: in I left the party because I was tired, because is the adverbializer. An adverbial clause construction with an adverbializer is an example of syndetic subordination. If the morpheme is affixed to a predicate, it is not an adverbializer but an overt marker of deranked status. (Section 15.3.2)

SIL Glossary
adverbializer
Quotation
"The original working definition of adverbial subordinators was the following: "free forms or bound morphemes which specify some semantic interclausal (or: circumstantial, adverbial) relation between the subordinate clause over which they operate and the modified matrix clause..." This scope has been narrowed down to an investigation of lexical markers, i. e. free forms, thus leaving aside bound conjunctional particles" (Kortmann 1997: 5) ❡ "[Adverbial subordinators:] morphemes which mark adverbial clauses for their semantic relationship to the main clause" (Dryer 2005: 382)
Sources
Dryer 2005; Kortmann 1997