sentence adverb

noun Grammar.
  1. an adverb modifying or commenting upon the content of a sentence as a whole or upon the conditions under which it is uttered, as frankly in Frankly, he can't be trusted.

Origin of sentence adverb

First recorded in 1890–95
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018