(online) The Semantics, Pragmatics, and the Lexicon section (under Linguistics) has chapters on Lexical Semantics, Semantics, Semantic Processing, Neural Basis of Semantic Knowledge, Deixis, Evidentials, and more. With lists for further reading. An excellent starting point.
Online lexical reference system from the Cognitive Science Laboratory, Princeton. English nouns, verbs, adjectives and adverbs are organized into synonym sets, each representing one underlying lexical concept.