Moder and fader are legal terms defined by The Swedish Tax Ministry's (Skatteverket's) praxis. Mamma and Pappa and Mor and Far are not. For example, in a lesbian couple, the mother who gives birth is legally designated as "moder" and the one who does not is registered as "förälder" (parent) if they are married. If they are not married she must adopt the child and is then registered as "vårdnadshavare" (guardian).
My partner and I are suing the Tax Ministry in a case over these terms which is why I know this. I'm a transgender man and am legally male, however since I gave birth to my daughter, the Tax Ministry registered me as "moder" instead of "fader." Interesting linguistic tidbit: in their initial defense, the Tax Ministry claimed that "moder" is a "könsneutrall begrepp" or a gender neutral term, but that "förälder" is gendered female because it is a term only allowed for non-birth mothers in lesbian couples. So far two courts have ruled that the Tax Ministry should change their registration of me to "fader" but the Tax Ministry has since appealed the case further to the Swedish Supreme Court (Högsta domstolare) where it sits now.
For comparison, the American consulate report of birth abroad (a version of a birth certificate) is actually gender neutral with the parental designations listed as "Mother/Parent" and "Father/Parent."
I know several landsting are supposed to be in the process of updating their systems to allow for e.g. transgender men being registered in midwifery journals and the like. Previous and/or current systems contain(ed) built-in limitations such as only allowing for female social security numbers. At least progress is being made, but it sure could go a lot faster.
Moder and fader are quite old-fashioned, mor and far somewhat so as well. Also sounds somewhat formal.
Mamma and pappa are common and most widely used. I would recommend any learner to use these.
Lastly, we have morsa and farsa which I think still qualify as slang even though they've been around for quite a while. They're very informal. Some think they're a tiny bit derogatory, but I personally don't think so at all (and I use them in my normal speech). Would not recommend you to use them for parents of people you don't know very well already.
It also depends on where you’re from I think. It’s more common in certain regions to use morsa and farsa.
I did a survey online a while back where I got 1000 replies on the usage of these words. Most the people where males in their 20s from various parts of Sweden and Finland.
The first question is what word people used to talk to their parents, and the second one when they talk about them. ”Vid förnamn” means ”by first name”.
Would it be altogether weird if I continue to use mor and far, though? I'm not on the habit of using informal terms for family in any languages (unless I am speaking directly to my own parents in private), so using the obviously familiar mamma and pappa makes me uncomfortable.
It’s not weird to use min mor/far at all; as you can see above, 1/10 of people (most of them in their 20s) do so, and the percentage would probably be higher for an older group. I do so myself and I know many who do so. I have a hunch it might be more common in southern Sweden.
For me, Mor and Far makes more sense to use when learning, because in my head when working out uncles, aunts, grandfathers, grandmothers etc, it's so much easier to work out: Mormor (mother's mother) or Morfar (mother's father), etc etc I literally read it in my head as the descriptions in brackets rather than the appropriate translation (gran and granddad respectively)
Only style. We mostly use mamma in Swedish, but some people use mor as well. (Those who don't typically find it old-fashioned.) And the plural of mamma is mammor, while the plural of mor is mödrar.
mor is actually a shorter form of the word moder, from which it takes its plural form, but moder is only used in terminology today (e.g. law, medicine), and archaic in everyday modern Swedish.
Sure, but for Android (kindle) version, it suggests the correct (or alternate) spellings for each word you type (and I can add Swedish words to the dictionary), where as in iOS - spell check is not available AT all. I've been marked wrong on iphone from the screen not recognising my touch so many times as well. I honestly don't think there should be so many technical discrepancies between the two platforms.