1 Vague words are very common on surveys. 2  A word is vague when it is not obvious to a respondent what referents (e.g., instances, cases, examples) fall under the umbrella of the word's intended meaning. Vagueness in Sentences and Words.  2 The primary application of 'vague' is to sentences, not to words. 3  But the vagueness of a sentence does not imply that vagueness of every constituent word.