The notion of semantic correctness (meaningfulness, or sensefulness) of propositions is widespread in logico-philosophical and linguistic works, as well as in experimental cognitive science. Nevertheless, its content is not clear. Many discussions connected to its use serve as evidence for its obscurity. In this investigation, I articulate and solve some interrelated problems which should be analyzed to make this notion more intelligible. Firstly, I pose a question whether semantic correctness is a normative or a descriptive characteristic. In other words: does it refer to a certain ideal of language usage ascribed to the abstract rational agent but not necessarily observed or even recognized by real agents (the normative option), or to some attitude of real language users towards linguistic expressions (the descriptive option)? I show that the notion of semantic correctness emerged in theoretical contexts as normative due to its role within certain conceptions of scientific rationality. However, one can say that it also contains a descriptive aspect, but it is needed to state distinctively what this aspect is. Particularly, there is a question: can the compatibility of ontological categories in the worldview of a language user (call it ontological correctness) be taken as a criterion of semantic correctness for natural languages? I show that this is inadmissible: ontological categorial mistakes should not be seen as semantic deviations because in this case it would be impossible to delimit senseless sentences from contradictive and simply false sentences in natural languages. Finally, I propose a novel view of the content of the meaningful/senseless dichotomy. It occupies a special place among semantic distinctions being related to structural laws of knowledge incrementation and discourse deployment. From this perspective, I outline an integral approach to the conditions of meaningfulness/senselessness of propositions considering a number of factors. In particular, I analyze the conditions of senselessness for contradictions and tautologies.