Exocentric
WordNet
adjective
(1) Not fulfilling the same grammatical role of any of its constituents
"When `until last Easter' serves as an adverb it is an exocentric construction"
WiktionaryText
Adjective
- (of a phrase or compound words) not having the same part of speech as any of its constituent words
- Example: The adverbal phrase with great care contains no adverbs.