Glasið er fullt af mjólk, en sykur vantar.

to be

Breakdown of Glasið er fullt af mjólk, en sykur vantar.

• en: but
• fullur: full
• af: of

Questions & Answers about Glasið er fullt af mjólk, en sykur vantar.

Why does glasið end with -ið, and what does that indicate?

The suffix -ið is the neuter singular definite article in Icelandic.

• glas (or eitt glas) = “a glass” (indefinite)
• glasið = “the glass” (definite)
  Because glas is a neuter noun, its definite form takes -ið rather than -inn or -in.

Why is the adjective fullt used here, and why does it have a -t ending?

fullur (“full”) is a three-gender adjective with these singular nominative forms:

• masculine: fullur
• feminine: full
• neuter: fullt
  Since glasið is neuter singular, the adjective must agree in gender and number, giving fullt.

What role does af play in fullt af mjólk, and could I use í or úr instead?

After fullur you use af + dative to express “full of [something].”

• fullt af mjólk = “full of milk”
  Using í would mean “in” (location) rather than “filled with,” and úr means “out of.” Only af correctly conveys “filled with.”