The paper deals with the Russian word odnaždy, treated as a marker of weak definiteness (i.e., epistemic inequality of the speaker and the addressee). Similarities and differences between odnaždy and odin are considered. As odnaždy is a discursive word, its semantics of weak definiteness is reflected in what might be termed introductivity, i.e., the necessity of continuing. But introductivity is characteristic only of thematic odnaždy. In a hypotactic context, as well as in the future tense, and in the scope of some operators, odnaždy becomes an ordinary tense marker expressing indefiniteness or nonreferentiality.