Adjective
(geology) Of or pertaining to metasomatism.
(entomology) Of or pertaining to the metasoma.
Source: en.wiktionary.orgThus, assigning age significance to a result requires studying the metasomatic and thermal history of the rock, any metamorphic events, and any evidence of fluid movement. Source: Internet
While difficult to be certain of derivation of pegmatite in the strictest sense, often pegmatites are referred to as "metamorphic", "granitic" or "metasomatic", based on the interpretations of the investigating geologist. Source: Internet