of Oxford Dictionary are you considering? There's a good few out there. I bought the Oxford Concise Dictionary and I find it excellent. I don't think I've ever looked up a proper* word and not found it. It's partly targeted at professionals so there are a lot of scientific words in there - like "cholinesterase" and "congruent". There's a lot of obscure words too - "cachinnate" (laugh loudly) and "sciolist" (me?
) for instance - so you know that the moderately advanced words you'll want to find will be in it.
The definitions are clear and non-moralistic. For example:
catamite - a boy kept for homosexual practises
In older dictionaries and some modern dictionaries the definition of catamite has a moral angle to it - not so here.
Some random definitions to illustrate clarity:
impeach - to call into questions the validity of (a practise).
impeccable - in accordance with the highest standards.
judgement - the ability to make considered decisions or form sensible opinions / an opinion or conclusion.
judgemental - having an excessively critical point of view.
scenery - the natural features of a landscape considered in terms of their appearance, especially when picturesque.
Some definitions, like catamite, also provide details of the origin of the word, which is nice.
*You won't find a definition for "omg", but you will find one for "lol".