Its archaic sense means to direct or turn the mind, eyes, thoughts, etc. It is this directedness of mental states toward objects and events in the world that gives intentionality its meaning in philosophy as aboutness, in reference to objects or states of affairs in the extensional world. The traditional meaning in philosophy is closely bound to assertions, in language and logic, about the world. Beliefs and desires are intentional, since they have grammatical objects. A belief is always a belief about something or that something is true.
Desire is always desire for something.
Moods and some other subjective states, though consciously experienced, may not seem to involve assertions or to be about anything in the world. But if carefully introspected, moods and all emotional states are found to have definite, localizable referents in the body. These are specific sensations to which the mind attributes a meaning, even if it cannot be verbalized. Sometimes this meaning can be brought into consciousness through suitable techniques. This is comparable to the effect of subliminal perception, which is known to be capable of producing anxiety and accompanying physiological changes.