Turkish is part of the Turkic family of languages, from Central/East Asia. It made its way to modern Turkey long after Roman times, where the Turkish speakers came up against (and eventually overwhelmed) the Byzantine Empire and supplanted the Greek language there (though not finally until the 1920's, when most of the last Greek speakers were driven out by the Turks). "Turkish" is used to refer to the language of Turkey itself, and "Turkic" for the language family of which it is a part. Most of the Turkic languages are still fairly close to one another, even though they are spoken from Turkey all the way to China. They separated from one another much more recently than many of the Indo-European languages did.

There were Celtic-speaking tribes who made their way east about 3 centuries BC, through Greek-speaking territory (which is when the Greeks gave them the name "Keltoi", based on what the Greeks heard them call themselves). Some of them eventually made their way to what is the central part of modern Turkey, where they founded a kingdom eventually called Galatia, with its capital at Ancyra (the modern day Turkish capital, Ankara, is its successor).

These were the people to whom the Apostle Paul wrote his Epistle to the Galatians, found in the New Testament, and they were apparently still speaking a Celtic language at that time (the epistle was written in Greek, of course, and most of them would probably also have spoken Greek by then). There are records of their Celtic language surviving into the 4th or 5th century AD, but not after that. They would probably all have become Greek speaking before the Turks made it to the area, though some of them might have been absorbed into other language groups, such as the Armenians or the Kurds who lived further east in what is now Turkey (both Armenian and Kurdish are also Indo-European languages). There would have been little or no continuing contact between the Galatians and Celts much further west, mainly because the Slavs later came into the Balkans and cut them off from the west, so there would have been no conduit for transferring Turkish/Turkic westwards through Celtic channels.

There are theories which might tie the Indo-European languages to the Turkic languages, but they are disputed and the break would have happened way before 5,000 BC, presumably somewhere in Central Asia. One theory posits that it happened after the ice started to melt in the last ice age, and related peoples in Central Asia were separated by a huge lake which developed, with the people on either side of the lake having separate language development from then on, until coming back into contact in modern times. It's just a theory, though.

Aer Lingus is Old Irish, lingus comes from the verb lingid meaning to jump/ leap. Aer Lingus means "sky jumper"

'Lingus' is supposed to be an anglicised form of 'loingeas' (= fleet), to make it more user-friendly for non-Irish speakers. I must say I prefer your version, Cian

I mean An Cionnfhaolach's etymology post. Ugh, is there no way to edit these posts?