The article aims to highlight specific features that enable the identification of a certain class of Polish adverbial expressions ending in -o/-e, which do not belong (unlike regular adverbs) to the object level of language, nor represent metatext in the manner that particles or sentential adverbs do. The paper thus discusses units such as iście [królewski] ‘truly royal’, dosłownie [idiotyczny] ‘literally idiotic’, jawnie [wrogi] ‘openly hostile’, etc. Although based on linguistic data from Polish, research hypotheses are more universal. The author introduces a set of tests to ensure precision in distinguishing unqualifiable meta-predicative adverbials from those units that are superficially similar. The following parameters are taken into account: (i) prosodic features, especially the relationship of a word and the sentence (non-contrasting) stress; (ii) position in the linear word order; (iii) possibility of being negated; (iv) capacity to combine with common adverbs in coordinate constructions; (v) capacity to combine with intensifiers, weakeners, or any other predicates in subordinate constructions; (vi) relationship to the grammatical category of the degree; (vii) range of syntactic and semantic combinability; (viii) ability to be used in a context with an ordinary adverb of the same shape. An important aim of this work is the examination of (a) relationships between the epistemic character of the expressions in question, (b) their belonging to the metalevel of language, and (c) their place in the theme-rheme structure of potential utterances where they may be functioning.