I've commonly heard the particle einmal as an adverb. Does it have a real meaning or is it just bitte?
Situations where I have heard of it:
By receiving an object
Einmal deinen Ausweis, oder, einmal zehn Euro, usw.
and
könntest du das einmal machen?
among others.
Comment: If it helps, I've heard einmal in the south part of Niedersachsen.
In the situation of könntest du das einmal machen?, "einmal" is meant as "eventually". Somehow the sentence is a short colloquial form of könntest du das irgendwann einmal machen? where eimal is a filler to emphasize that könntest, but probably that historically comes from counting that action regarding to "eventually".
Grimms etymologisches Wörterbuch underpins that (see here: at B) 3.)).
Although I'm not very happy with it, since it's missing nicht einmal = not even and because of what I think I had to add in the grey passages, Here's a little excerpt from Duden onlines main article on einmal:
1. a. ein [einziges] Mal
Beispiele
- einmal und nicht wieder
- noch einmal (ein letztes Mal)
- "noch einmal" can also mean "ein weiteres Mal", depending on the emphasis laying on "ein" or not- ein- bis zweimal
- einmal ums/übers andere (veraltend; dauernd, immer wieder)
- einmal sagt er dies, ein andermal das
- noch einmal (doppelt) so groß
- es hat sich einmal mehr (wieder einmal; nach englisch once more) gezeigt, dass…
Wendungen, Redensarten, Sprichwörter
- auf einmal (auf)
- "auf einmal" means "all of a sudden" except in some rare cases- einmal ist keinmal (es ist bedeutungslos, so gut wie nicht geschehen; oft als Entschuldigung für ein bewusstes, aber als einmalige Ausnahme vom sonstigen Wohlverhalten angesehenes Fehlverhalten)
1. b. zum einen; erstens
Beispiel
- einmal wegen des schlechten Wetters, dann aber auch aus Zeitgründen
2. a. eines Tages, später
Beispiel
- er wird es [noch] einmal bereuen
2. b. vor längerer, langer Zeit, einst, früher
Beispiel
- es war einmal … (formelhafter Anfang von Märchen)
2. c. irgendwann; Kurzform: mal (2)
Beispiele
- kommen Sie doch einmal zu mir!
- (verblasst) wir wollen einmal sehen
As you can see, einmal has a broad variety of meanings depending on the sentence surrounding the word. However, it does not have the same meaning as bitte as far as I know (being a native Swiss German speaker).
For an expanded list of articles on the meaning of einmal, check out the Duden online search for einmal here.
Einmal, meaning "one time" (a delicious specimen of Denglish used by tourists wearing "Jack Wolfskin" jackets, "basecaps" sandals and socks) is a mean to emphasize the substantive associated with it.
Just like its friend "zweimal", einmal is likely to be heard in situations requiring "perfekt" understanding of what is beeing said. "zweimal Kaffee bitte" would be said in a noisy restaurant, instead of zwei Kaffees bitte (this is my opinion, but there certainly is a more grammatical reason). "könntest du das einmal machen?" is also a very good example of the emphasis implied by einmal. It is sometimes abbreviated and read 'mal.
Also nicht einmal = not even (the emphasis again).
Apart from this "einmal" is also used to translate the English word "once"...
It can also translate the English construction "used to" to describe a distant past :
Ich war einmal ein Kind. = I once was a child.
"Es war einmal eine Prinszessin in einem weissen Schloss, bla bla bla"
Einmal can mean a lot of things. In the first sense, einmal is really just saying once, or firstly. For example:
Einmal Schnitzel mit Pommes.
Bzw. "zweimal" if you want two. The same goes for paying or asking for other things, though I've most commonly heard it while dining out.
For the second question: Kannst du das einmal machen?
In this case einmal is sometime or eventually. If someone were to ask you to do something once, they would probably ask something like
Kannst du das dieses Mal machen?
or something like that.
I'd suggest looking at the Pons dictionary for more examples. Also, don't make the mistake of translating and getting hung up on the details. You'll learn by listening carefully and asking (politely) for people to correct your mistakes.
The general meaning of einmal is one time.
In the situations you described you can't say it is equivalent to bitte. In nearly every situation you can omit it (expect you really mean only one time), but it sounds nicer with it and it isn't too formal.
Btw., in your sentences you would always add bitte to the end, otherwise it's too rude.
