Learn Hardcore Icelandic: Sendu mér símanúmerið, vinsamlegast.

It’s the second-person singular imperative of að senda (to send). Imperatives give direct instructions: Sendu = “(You) send!” The plural imperative is Sendið (“You all send!”). Using vinsamlegast (“please”) softens the command.

Why is it mér and not mig?

Icelandic marks the recipient of “sending” in the dative case: senda e-m e-ð (“send something to someone”). Mér is the dative of “I” (ég). Mig is the accusative and would be used if “me” were the direct object (e.g., “send me [as the thing]”). So: Sendu mér símanúmerið = “Send the phone number to me.”

What does the ending -ið in símanúmerið mean?

It’s the attached definite article for neuter nouns (“the”). Símanúmer = “phone number”; símanúmerið = “the phone number.” Here it’s the direct object, so it’s in the accusative neuter singular, which looks the same as nominative in neuter.

Is símanúmer a compound word?

Yes. It’s síma- (the genitive form of sími, “telephone”) + númer (“number”). The head is númer, which is neuter; the definite article attaches to the end: símanúmerið. Icelandic compounds are written as one word (no hyphen): símanúmer, not “síma númer” or “síma-númer.”

Is the word order Sendu mér símanúmerið the only option?

It’s the most natural. Icelandic prefers the indirect object pronoun (mér) before the direct object noun (símanúmerið): Sendu mér símanúmerið. You can move things for emphasis, but Sendu símanúmerið mér sounds marked or odd in everyday speech. With a pronoun direct object, you still usually say: Sendu mér það (“Send it to me”).

How polite or formal does vinsamlegast sound? Where can it go?

Vinsamlegast literally means “most kindly” and often feels formal or notice-like (“Please do X”). It’s fine in messages but can sound stiffer than everyday English “please.” Placement:

Start: Vinsamlegast sendu mér símanúmerið.
End: Sendu mér símanúmerið, vinsamlegast. Both are common. It’s often separated by a comma when placed at the end, but the comma is optional.

Are there more natural everyday alternatives to make the request softer?

Yes. Common choices:

Geturðu sent mér símanúmerið? (“Can you send me the phone number?”)
Gætirðu sent mér símanúmerið? (“Could you send me the phone number?” — a bit softer)
Væri mögulegt að senda mér símanúmerið? (more formal/indirect) Colloquially, you might also see plís (borrowed from English “please”).

What changes if I’m talking to more than one person?

Use the plural imperative: Sendið mér símanúmerið, vinsamlegast. If you mean “your phone numbers,” specify plural “your”: Sendið mér símanúmerin ykkar (“send me your phone numbers”). For one person’s number: símanúmerið þitt (“your [singular] phone number”).

How do I say “Don’t send me the phone number”?

Use the negative imperative pattern with the infinitive: Ekki senda mér símanúmerið. (Literally “Don’t send to me the phone number.”)

Could I say Sendu símanúmerið til mín?

Grammatically possible, but it sounds unusual for this kind of request. Til mín (“to me”) focuses on destination. With senda, the natural way to mark the recipient is the dative pronoun: mér. Prefer Sendu mér símanúmerið.

Pronunciation tips for tricky parts?

Sendu: the u is a short, rounded vowel (like German “ü” but shorter). The nd often sounds like [nt].
mér: é is like “yeh” with a glide; many learners hear it as “myer.”
símanúmerið: main stress on the first syllable (sí-). í is long “ee,” ú is long “oo,” and final -ið has ð as the soft “th” in “this,” often very light.
vinsamlegast: stress on the first syllable (vin-). The g is a normal hard “g,” and the final -ast is pronounced clearly.