In linguistics, a disjunct is a type of adverbial adjunct that expresses information that is not considered essential to the sentence it appears in, but which is considered to be the speaker's or writer's attitude towards, or descriptive statement of, the propositional content of the sentence, "expressing, for example, the speaker's degree of truthfulness or his manner of speaking.
Here are some examples (note: the disjuncts that follow are 'sentence adverbs'): Sometimes, the same word or phrase can be interpreted either as a disjunct or as a simple adjunct: An example of a sentence adverb modifying a sentence is: Unfortunately, when I got to the supermarket it had run out of the vegetable I like.
For instance, Washington State University English professor Paul Brians writes:When speakers are trying to impress audiences with their rhetoric, they often seem to feel that the extra syllable in “importantly” lends weight to their remarks: “and more importantly, I have an abiding love for the American people.” However, these pompous speakers are wrong.
It is rarely correct to use this form of the phrase because it is seldom adverbial in intention.
The same applies to “most importantly”; it should be “most important.”[3] However, Merriam-Webster write:American commentators seem to object to the adverb and recommend the adjective.