Question: What is a comprehensive definition of Philosophy? Alternatively, is it impossible to define Philosophy? This is a pseudo-[meta](https://philosophy.meta.stackexchange.com/) question, but it seems like it belongs here.

Answer: 
I think Wittgenstein is very illuminating in this respect. Some relevant quotations, dealing with some aspects of the question (PI stands for *Philosophical Investigations*):

> 
> PI§109 [...] Philosophy is a battle against the bewitchment of our intelligence by means of our language.
> 
> 
> PI§126 [...] One might also give the name "philosophy" to what is possible *before* all new discoveries and inventions.
> 
> 
> PI§127 The work of the philosopher consists in assembling reminders for a particular purpose.
> 
> 
> 

And as far as philosophy speaking of itself posing a problem:

> 
> PI§121 One might think: if philosophy speaks of the use of the word "philosophy" there must be a second-order philosophy. But it is not so: it is, rather, like the case of orthography, which deals with the word "orthography" among others without being second-order
> 
> 
> 

In general I highly recommend anyone troubled by the question 'What is philosophy?' to read PI§89-138 - one of the most brilliant self-reflections on the purpose and nature of philosophy in the history of thought. Of course you have to be minimally aware of the context of Wittgenstein's thought, but I feel these passages are elucidatory nonetheless.
Here are some *popular definitions of philosophy*.

The word "philosophy" comes from the Greek φιλοσοφία (philosophia), which literally means "**love of wisdom**"

*[Philosophy](http://en.wikipedia.org/wiki/Philosophy) is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. It is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational argument.*

Webster says,

***Philosophy** is the love of, or the search for, wisdom or knowledge. It's theory or logical analysis of the principles underlying conduct, thought, knowledge, and the nature of the universe"*

Another [dictionary](http://www.merriam-webster.com/dictionary/philosophy?show=0&t=1307827998) says,

*Philosophy is the most basic beliefs, concepts, and attitudes of an individual or group* 

[More...](http://www.etymonline.com/index.php?search=philosophy&searchmode=none)