There is the only source of our knowledge. Space-time. And this is all what meaning is about. Period. It seems like very evident point. But namely so no one does not proceed further. There is a lot of theories which tried to interpret a language and a thinking. But they all lack a basis which they all ground on. There is only one source of meaning. Meaning is a direct descendant of space-time and consists of:
(a) nouns, objects, anything which corresponds to space,
(b) verbs, actions, anything which corresponds to time,
(c) noun relations, adjectives, anything which links space entities,
(d) verb relations, adjectives, adverbs, modality, anything which links time entities.
Why these four? There is space-time and two constituents. Because intellect (which is a producer of meaning) could not (and should not) to keep the entire space-time which was lived through, it reduce information and stores not objects and actions but only relations between them. All the rest is only derivatives of these four entities.