Learn Icelandic: Eru þau veik? - Are they neuter sick?

Icelandic has three words for 'they' depending on gender. You use þeir for an all-male group and þær for an all-female group. Þau is the neuter form, used when talking about a mixed-gender group (like a brother and sister) or a group of neuter nouns.

Is the verb eru used for all versions of 'they'?

Yes! While the pronoun changes based on gender (þeir, þær, or þau), the verb remains the same. They all use eru for 'are'.

Why is the adjective veik used here instead of veikir or veikar?

Adjectives in Icelandic have to match the gender and number of the noun or pronoun they describe. Because the subject þau is neuter and plural, the adjective changes to its neuter plural form, which is veik. If it were a group of men, you would use veikir, and for a group of women, veikar.

Doesn't veik also mean 'sick' for a single female?