Joan Garrod & Tony Lawson 
Dictionary of Sociology [PDF ebook] 

With full coverage of areas such as social stratification, crime and deviance, culture and identity, mass media, power and politics, and religion, the Dictionary of Sociology is designed to give the reader a sound introduction to the debates and issues in which sociologists engage. Cross references abound, while illustrations and tables further aid understanding and the A-Z format makes the book exceptionally easy to use.