My compliments on a very interesting thread. May I go off topic for a moment and ask those who have problems with the use of the word "Celtic" to describe music if they also have problems with the use of that term in etymology {the study of name origins and meanings}.

There are a number of websites on name origins & meanings that use the terms "Celtic"; or "Gaelic"; or "Celtic/Gaelic"; or "Irish Gaelic", or "Scottish Gaelic". Some websites use both "Irish" and "Irish Gaelic" or a website for Irish names uses the Gaelic term. See this example from http://www.ireland-information.com/heraldichall/irishboysnames.htm:

Name: Liam
Gaelic Equivalent: Liam
Meaning/Origin: Gaelic form of William

-snip-

I'm confused. Is Irish Gaelic and Irish interchangeable terms? Or is "Irish Gaelic" older than "Irish"? I asking because I post information about name meanings on my website and I want to use the best citation for Irish and/or Scottish names. Which would you suggest I use?

Also, here are two excerpts from a website that I found on http://www.answers.com/topic/scottish-gaelic-language

"Scottish Gaelic
...
Spoken in: Scotland, Canada   
Region: Scottish Highlands, Western Isles, Cape Breton, Nova Scotia; formerly all of mainland Scotland except the south-eastern part (parts of Lothian and Borders}
...
Language family: Indo-European
Celtic
Insular Celtic
   Goidelic
    Scottish Gaelic"
-snip-

"Scottish Gaelic (Gàidhlig) is a member of the Goidelic branch of Celtic languages. This branch includes also the Irish and Manx variants. It is distinct from the Brythonic branch, which includes Welsh, Cornish, and Breton. Scottish, Manx and Irish Gaelic are all descended from Old Irish. The language is often described as Scottish Gaelic, Scots Gaelic, or Gàidhlig to avoid confusion with the other two Goidelic languages. Outside of Scotland, it is sometimes also called Scottish or Scots. This usage is uncommon in Scotland, because in recent centuries the word Scots has by-and-large been transferred to the version of Middle English that had become the Scots language"...

-snip-   

Do folks here agree with this information? And [returning this to a music theme] are there similarities between the traditional music found in Scotland and the Canadian provinces settled by Scottish people?

Sorry for this interruption. Hopefully, this doesn't detract that much from the main discussion.

Thanks in advance for any help you can give me to get a clearer understanding of the differences {if any} between these terms.

Azizi