Interlanguage- ratologism

Finally got down with the definition of "Interlanguage."

So, when someone tries to learn a second language, hypothetically, this interlanguage system gets created as the learner tries to get closer and closer to the form of the target language-- da second language.

The problem... experts say that you are out of luck if you start the process of really use da second language later than childhood...

Since I didn't start living in an all English setting till my early adulthood, guess I am entitled to da ratologism de moi? 8-O lol

pneumocephalic and pneumocephalon

What do I mean when I use the word pneumocephalic? 

I made it up years back because I put pneumo (i.e., Air; gas) and cephalic (i.e. related to the brain) to represent this other concept called "air head."  An adjective it is.

Only to know later that there is a health condition called Pneumocephalus where there is presence of air or gas in patient's cranial cavity.  

Since pneumocephalus is a proper medical term and people do suffer from it, I did not have the audacity to use the word pneumocephalus when converting my "pneumocephalic" to a noun.  Instead, I chose to use the word pneumocephalon.

Diphthong

Two vowels together makes a diphthong /ˈdɪfθɒŋ/.