Λόγος as "discourse" means rather the same as δηλοῦν: to make manifest what one is 'talking about' in one's discourse.1 Aristotle has explicated this function of discourse more precisely as ἀποφαίνεσθαι. The λόγος lets something be seen (φαίνεσθαι), namely, what the discourse is about; and it does so either for the one who is doing the talking (the medium) or for persons who are talking with one another, as the case may be. Discourse 'lets something be seen' ἀπό ...: that is, it lets us see something from the very thing which the discourse is about.2 In discourse (ἀπόφανσις), so far as it is genuine, what is said [was geredet ist] is drawn from what the talk is about, so that discursive communication, in what it says [in ihrem Gesagten], makes manifest what it is talking about, and thus makes this accessible to the other party. This is the structure of the λόγος as ἀπόφανσις. This mode of making manifest in the sense of letting something be seen by pointing it out, does not go with all kinds of 'discourse'. Requesting (εὐχή), for instance, also makes manifest, but in a different way.
When fully concrete, discoursing (letting something be seen) has the character of speaking [Sprechens]—vocal proclamation in words. The  λόγος is φωνή, and indeed, φωνή μετὰ φαντασίας—an utterance in which something is sighted in each case.
And only because the function of the λόγος as ἀπόφανσις lies in letting something be seen by pointing it out, can the λόγος have the structural form of σύνθεσις. Here "synthesis" does not mean a binding and linking together of representations, a manipulation of psychical occurrences where the 'problem' arises of how these bindings, as something inside, agree with something physical outside. Here the συν has a purely apophantical signification and means letting something be seen in its togetherness [Beisammen] with something—letting it be seen as something.
Furthermore, because the λόγος is a letting-something-be-seen, it can therefore be true or false. But here everything depends on our steering clear of any conception of truth which is construed in the sense of 'agreement'. This idea is by no means the primary one in the concept of ἀλήθεια. The 'Being-true' of the λόγος as ἀληθεύειν means that in λέγειν as ἀποφαίνεσθαι the entities of which one is talking must be taken out of their hiddenness; one must let them be seen as something unhidden (ἀληθές); that is, they must be discovered.3
1 '... offenbar machen das, wovon in der Rede "die Rede" ist.'
2 '... von dem selbst her, wovon die Rede ist.'
3 The Greek words for 'truth' (ἡ ἀλήθεια, τὸ ἀληθές) are compounded of the privative prefix ἀ- ('not') and the verbal stem -λαθ- ('to escape notice', 'to be concealed'). The truth may thus be looked upon as that which is un-concealed, that which gets discovered or uncovered ('entdeckt').