def define(self, pos=None):
<EOL>raise NotImplementedError<EOL>
Return a list of definitions for this word. Each definition
        corresponds to a synset for this word.

        :param pos: A part-of-speech tag to filter upon. If ``None``, definitions
            for all parts of speech will be loaded.
        :rtype: List of strings

        .. versionadded:: 0.7.0 (``textblob``)