Wordpower is a learner's dictionary for intermediate students.

It comes in paperback and is usually sold with a Genie CD (quick-consultation, small-interface electronic version).

Oxford Wordpower Dictionary
Second Edition
Oxford University Press

ISBNs
Paperback 0-19-431516-9
Paperback with Genie CD-ROM 0-19-431579-7

Intermediate

The Genie CD-ROM comes free with the paper version.

This program gives the entire text of Oxford Wordpower in this small interface for quick consultation. Passing your mouse over text calls up the definitions automatically (i.e. without clicking). This is very useful if you read English on the internet. Clicking on the speaker symbol gives you the pronunciation of the headword. Genie can be installed completely on your hard disk.