Please read tips and notes for food 1.
Vocabulary: obiad and kolacja
Obiad is the main meal of the day, usually eaten around midday (12AM to 4PM). It is usually translated as lunch (because of the time of the day when it is eaten), sometimes as dinner (since it is the main meal which is often eaten socially – with family members, in a restaurant etc.)
Kolacja is a medium-sized evening meal, usually eaten between 6PM and 9PM. Again, since the conventions for naming a meal of this kind in English vary, it can be translated in two ways: as dinner or supper.
If you eat dinner at evening - for you proper word for dinner is kolacja.
In the south-east it depends how the next word begins, but according to https://pl.wikipedia.org/wiki/Ubezdźwięcznienie in Warsaw dialect, that is "standard Polish", they always change it.
In the linked article is also a list of consonants that change from voiced(first ones)- to voiceless ( second ones). This happens at the end of word, and after voiceless consonant.
It's not so simple. ;-) Polish, like all Slavic languages with exception of Ukrainian and standard Serbo-Croatian features word-final devoicing, with one exception – prepositions are never devoiced.
Now, the problem starts, when there shouldn't be terminal devoicing, that is when obstruent is followed by either vowel or sonorant – in 'standard Polish'(understood here as "how Poles actually speak") there is voicing in such a situation. But in prescribed 'Literary Polish' what happens is, there is also devoicing in that position which leads to absolutely all obstruents being devoiced at the end of the word(with the exception of prepositions).
Now, indeed the Masovian dialect happens to coincide with the prescribed Literary Language, but that kind of pronunciation is still substandard, simply because:
As can be seen on the map, more than 60%(almost 2/3) of Polish speakers do not devoice before vowel or sonorant – you can hardly call a standard something that is done by minority of speakers, even if it is prescribed by dictionaries(most of which happen to be edited by people residing in Warsaw ;-) ). ;-P
Seriously, while normally I do not engage in "dialect wars" and accept regional things as regional, in this particular case, to paraphrase Polish idiom, if more than 60% of speakers tell you that you are drunk, go lay down already. ;-) Usus triumphs all, especially since it is the phonetically correct way in this case(if you look at the phonology of the Proto-Slavic, that is).
Yes, that is not a regional but "gwara" feature, that just happens to share isogloss with voicing/devoicing – if you want to read more: "Fonetyka międzywyrazowa zróżnicowana regionalnie". just noticed the link doesn't work directly – you will have to manually click "Leksykon" and go to page 2 there, sorry[/edit]
As for variance within dialect, it is normal, just like there are differences in how strongly the other part of the country is voicing and just to be clear – I don't have any problems with how Masovians are speaking, I just object to the fact it is prescribed as norm in Literary language, even through it is clear(based on popularity) that either both should be accepted as norm or the voicing one should be, simply because that is what usus would dictate. ;-)
lunch (American English)
dinner (British English)
午饭or午餐or中午饭or中饭(Chinese, from 12 to 1 pm in South China)
dinner (American English)
supper (British English)
晚饭or晚餐 (Chinese, from 6pm to 8pm in South China)