| Definition -
Pertaining to a group of syntactically related words of which none individually perform the same function as that performed by the group as a whole.
For example, none of the words in the phrase on the table is an adverb, yet as a group they form a phrase that functions like an adverb.
1. As opposed to endocentric, which pertains to a group of syntactically related words of which at least one performs the same function as that performed by the whole group.
For example, the noun shoe in the noun phrase the old shoe is endocentric because being a noun it has the same grammatical function as the noun phrase.
Etymology - The word derives from the Greek exo, outside + kentrikos, pertaining to a center.