Is “Complementiser” a Scrabble word?
Yes
COMPLEMENTISER
Valid in at least one Scrabble dictionary
Valid in these dictionaries
SOWPODS / CSW
Scrabble UK & International
TWL / NWL
Scrabble North America
Large English Dictionary
General English word list
Meaning of Complementiser
noun
1.A subordinating conjunction that can convert a clause into a complement clause, i.e. one that completes a grammatical construction in the predicate and that describes or is identified with the subject or object.
“"That" is a complementizer in the sentence "Mary believes that it is raining".”