Bíddu eina sekúndu.

Bíddu is the singular imperative of bíða, which means to wait.

So if you are speaking to one person, bíddu means wait!

In this sentence, Bíddu eina sekúndu is the natural way to say Wait a second or Hold on a second to one person.

Bíða is the infinitive, meaning to wait.

Bíddu is the form used when you are telling someone to wait. In other words:

• bíða = to wait
• bíddu = wait! (to one person)

The spelling change is just part of how this verb forms the imperative.

Eina is a form of the number einn, meaning one.

In this sentence, it corresponds to English a or one in a second / one second.

It appears as eina because it has to match sekúndu in:

• gender
• number
• case

So it is not the basic dictionary form einn here.

Because both words have changed form to fit the grammar of the sentence.

The dictionary form is:

• sekúnda = second (feminine singular nominative)

But in Bíddu eina sekúndu, the phrase is being used as a time expression, and Icelandic commonly uses the accusative for that. So:

• sekúnda becomes sekúndu
• einn becomes eina

Since sekúnda is feminine, the number one must also take the feminine accusative singular form: eina.

It is grammatically the word one, but in this sentence it works very much like English a.

So eina sekúndu can be understood literally as one second, but in natural English it is usually translated as a second.

That is normal, because Icelandic does not have a separate indefinite article like English a/an.

A very rough English-style approximation is:

BEE-du AY-na SEH-koon-du

A few helpful points:

• í sounds roughly like ee in see
• ei sounds roughly like ay in say
• Icelandic normally stresses the first syllable of each word

So an English speaker should be careful not to put the main stress later in sekúndu.

It is a very natural everyday sentence, and by itself it is not automatically rude. But like English Wait a second, the tone of voice matters.

It can sound:

• perfectly normal and casual
• a bit abrupt if said sharply

If you want to sound softer, Icelandic often uses things like:

• Bíddu aðeins. = Wait a moment / Just wait a bit
• Geturðu beðið aðeins? = Can you wait a moment?

So Bíddu eina sekúndu is fine, but politeness depends a lot on context and tone.

Yes. Bíddu is often used the same way English speakers use wait, hold on, or hang on.

So it does not only refer to literally waiting for time to pass. It can also be used conversationally, for example when you want someone to pause for a moment before continuing.

To more than one person, you would usually say:

Bíðið eina sekúndu.

So the difference is:

• Bíddu = wait! to one person
• Bíðið = wait! to more than one person

Modern Icelandic usually does not rely on a special everyday formal you the way some other European languages do, so the main distinction here is singular vs. plural.