Learn Hardcore Icelandic: Þau borða saman.

Þ is like the unvoiced th in English thin.
ð (in borða) is like the voiced th in this.
au (in Þau) is a diphthong roughly like the oy in boy, but with rounded lips.
Stress is on the first syllable of each word: ÞAU bór-ða sá-man (Icelandic generally stresses the first syllable).

What exactly does þau mean, and how is it different from þeir and þær?

þeir = they (all male)
þær = they (all female)
þau = they (mixed genders or when the group corresponds to a neuter plural noun like börn “children” or hjón “a married couple”) Modern speakers often prefer þau for mixed/unspecified groups for inclusivity. If it’s definitely all men, use þeir; all women, þær.

Can þau refer to just two people, like a couple?

Yes. þau is plural and can refer to any group of two or more. It’s very common for couples, especially because the word hjón (married couple) is neuter plural: þau hjónin “the couple.” Even without a noun, þau can stand for “they (that couple).”

Is þau ever singular, like English singular “they”?

No. þau is strictly plural in standard Icelandic. For a gender-neutral singular pronoun, many people now use hán; older style is hann eða hún (“he or she”).

Why is the verb borða not borðar here?

Because the subject is third person plural (þau), and the present tense 3rd plural form of regular -a verbs is the bare stem with -a: borða. Compare:

1st sg: ég borða
2nd sg: þú borðar
3rd sg: hann/hún/hán borðar
1st pl: við borðum
2nd pl: þið borðið
3rd pl: þeir/þær/þau borða

What part of speech is saman, and where does it go?

saman is an adverb meaning “together.” In a simple main clause it typically comes after the verb (and often after a direct object if there is one):

Þau borða saman.
Þau borða kvöldmat saman.

Can I put saman at the start for emphasis?

Yes. Icelandic is a V2 language, so if you front saman, the finite verb still comes second:

Saman borða þau. (Emphasizes the “together” part.)

Does this sentence mean a habitual action or something happening right now?

The Icelandic present can express both:

Habitual: “They (usually) eat together.”
Right now: “They are eating together.” To make “right now” explicit, use the progressive construction: Þau eru að borða saman.

How do I negate it?

Place ekki after the finite verb:

Þau borða ekki saman.
Progressive: Þau eru ekki að borða saman.

How do I turn it into a yes/no question?

Invert to verb-first (keeping V2 in mind):

Present simple: Borða þau saman?
Progressive: Eru þau að borða saman?

How do I say it in the past or future?

Past: Þau borðuðu saman. (“They ate together.”)
Future (with modal/auxiliary): Þau munu borða saman. / Þau ætla að borða saman.

Does borða need an object?

No. It can be intransitive (“eat”) or take an object:

Intransitive: Þau borða saman.
With object: Þau borða kvöldmat saman. (“They eat dinner together.”)

Are there alternatives to borða?

eta = “eat” (more formal/archaic; also used of animals in some contexts)
narta = “nibble”
matast = “have a meal/dine” (reflexive-style verb, less common in everyday speech)

What are the case forms of þau?

Nominative: þau (subject) – Þau borða saman.
Accusative: þau – Ég sá þau. (“I saw them.”)
Dative: þeim – Ég gaf þeim mat. (“I gave them food.”)
Genitive: þeirra – Maturinn þeirra (“their food”)

Any spelling or capitalization tips?

Þ/þ and Ð/ð are distinct Icelandic letters; don’t replace them with Th or D in proper Icelandic spelling.
Capitalize Þau only at the start of a sentence; otherwise þau.