To add a bit more context, "dík" is very informal, and might be considered a little rude when thanking someone who is not a friend.
"Díky" is also informal, but not as much, so when said in a light tone of voice and with a smile, can be appropriate even with strangers.
In formal settings, however, stick to the full form, "děkuji".
And then there is the supershort "ď" (note that it's Ď, not D). It's used only between close friends or family members, and even so, it's quite rare. I mostly only use it with my mother. It's roughly equivalent to the British "ta", which is also quite rare.
So in the descending order of formality, we have:
děkuji - děkuju - díky - dík - ď
I grew up with a Ukrainian father who taught me the basics of Ukrainian pronunciation. I was taught that there were two different shapes of e, the e shaped like e softened some consonants like d so I am used to inserting an invisible y between d and e. By the way, I love learning Czech.
Czech does not have any Polish nasal vowels (ę ą).
The audio (machine generated, NOT a recording) may not be perfect, but is still among the reasonable ones. There are unfortunately some, where the computer had much larger problems pronouncing them.
You can always check real people's recordings at different sites such as forvo.com.
They are both used to show gratitude, but "thank you" is more formal than "thanks".
In Czech, the full, formal variant is "Děkuji." (Thank you.)
The short, less formal version is "Díky." (Thanks.) You would usually use "díky" when talking to friends or family, but not when thanking a stranger or a person in authority.
"Děkuji" conveys more respect.
No - you just experienced the difference between standard written Czech and what people actually speak.
If you speak written Czech, you'll be understood but will "sound like a book".
A vague comparison might be someone who speaks completely without contractions in English. "I am not sure what you are talking about" versus "I'm not sure what you're talking about" -- understandable and completely grammatical but not that natural in speech.
The "děkuji" variant is a higher-register formal, while "děkuju" is infomal. Both are included in standard Czech, and there are many verbs that do this. The effect also applies to plural 3rd person forms, děkují (formal) vs děkujou (informal).
"Děkujem" is a non-standard variant of "děkujeme", meaning "we thank". It all goes to the lovely system of Czech verb conjugation.
Here you can hear the formal version (děkuji) a bunch of times, in one of the best demonstrations of how beautiful Czech can be.
This might sound strange, so I hope you are sitting down. Since I have always known that thank you and dekuji are the same, I have never really thought of dekuji as a "verb". I has stood in isolation, as a single tree in a field. Now that you alert me to the obvious, I am embarrassed, but undaunted.
Lovely song. FYI, I have found a couple of CZ radio stations that I stream via the internet (Tune In Radio app), to help give me more exposure to the language. I enjoy all the many different flavors of music that I am finding.
Yes, the verb is "děkovat". It's natural that you first learn these common phrases separately and only later connect them to the rest of your knowledge.
Are you also aware that "děkuji/děkovat" and "thank" are related and both come from the same ancestor. The nasal sound (/n/) disappeared from the Czech verb, and English changed the /d/ into a /th/ (German has "danken"), while Czech palatalized the /d/ into a /ď/.
I made this map that shows the relatedness a long time ago:
(Here's the link if you need to magnify it: https://i.imgur.com/jJYHhFF.png)
What's interesting about it is that we have these boxes in our heads - Germanic, Slavic, Romance... But many words don't follow that grouping - such as "thanks" being shared between Germanic, West-Slavic, and East-Slavic (except Russian), plus partially one of the Baltic sisters, not South-Slavic is completely separate and the Romance languages are split.
No, there is no dialect that would use that. "děkujim" is clearly just misheard "děkujem" which is a very common non-standard form of "děkujeme" (1st person plural) which is used most of the time when you say thank you on behalf of more than 1 person - for example when you're sitting in a café with a friend and the waiter brings coffee for both of you, you say "děkujem(e)" - then your friend doesn't need to say anything, because you've already thanked for them, although they will sometimes also say "děkujem(e)".