M.A.K. Halliday & Colin Yallop 
Lexicology [PDF ebook] 
A Short Introduction

This readable introductory textbook presents a concise survey of lexicology. The first section of the book is a survey of the study of words, providing students with an overview of basic issues in defining and understanding the word as a unit of language. This section also examines the history of lexicology, the evolution of dictionaries and recent developments in the field. The second section extends this study of lexicology into the relationship between words and meaning, etymology, prescription, language as social phenomenon and translation.
Lexicology: A Short Introduction will be of interest to undergraduate students of linguistics.