Where should one suggest new terminology? What is the proper place to suggest Bitcoin-related terminology that one believes should be used by the community? For example, when one wants to standardise some terms people use to describe different things, or coin a new term to describe something that wasn't yet described?
Bitcoin is completely decentralized.  Most terms in use today "pools", "51% attack", "miner", "rigs", "stales" came about simply because they were adopted by most users of bitcoin.

In addition to the IRC options already given, http://bitcointalk.org has a general discussion forum which may finds some interest if you start a "glossary" thread.

Alternatively you could look to influencing the discussion via the bitcoin wiki.  You can add entries for existing terms, clarify terms, request terms be merged with othe terms in an attempt to improve standardization.

Just remember bitcoin is decentralized.  You can only gain adoption by winning mind share.  You can't force a term by committee.