#def -- To tag human readable definitions of a #hashtag
#def #MyHashTag Human readable definition or the URL to it
This tag is to introduce a convention rather than a syntax. It is meant to give user a quick and flexible way to find (or define) meanings of a hashtag. It doesn't have to be positional and should allow free form tagging for deeper namespace. To improve Signal / Noise ratio, It is recommended to use #def only in a microblog notice (tweet) related to a #hashtag definition.
A possible usage of #def is that a user can search a combination of #def + #MyHashTag to obtain a definition or a list of definitions about #MyHashTag. If no satisfying definition is available, the user can create a new one and it will automatically added to the list because of the appearance of both tags.
#def #twsearch http://search.twitter.com #def #htwikia http://hashtags.wikia.com #def #def http://hashtags.wikia.com/wiki/def