This is one for the desktop or your briefcase. Their books are popular because they generally make clear page layout a priority. The Collins Pocket Dictionary contains 44,500 definitions, plus advice on grammar and common problems. Amazon.co.uk Amongst the 'portables', the Heinemann English Dictionary is specially designed for use in schools. Not only is each entry very clearly presented, but parts of speech are spelt out in full, not abbreviated as is usual in dictionaries.
Pronunciation is explained, and there are pull-out boxes with gems of etymology on certain words.
It has been created with the UK National Curriculum in mind - and has proved to be popular as a reference for the classroom. If you are buying a dictionary for serious use, paperbacks can be a false economy. Very often, hardback editions only cost slightly more - and they will last you a lifetime. Moving up into the more serious size of dictionary, the New Oxford focuses on English as it is really used in the late 20th century, informed by available evidence and thinking. Its defining style makes it possible to give the most complete picture of English as it is used today, providing authoritative and comprehensive coverage of the language.