Demonstrative plural (þessir, þessar, þessi)

When pointing out multiple items ("these"), the demonstrative pronoun þessi must match the noun's gender, number, and case. Here are the plural forms for the nominative (subject) and accusative (direct object) cases:

GenderNominativeAccusative
Masculineþessirþessa
Feminineþessarþessar
Neuterþessiþessi

Notice that only the masculine form changes between the subject and direct object!

Masculine: þessir and þessa

For masculine nouns like kassi (box) or poki (bag), use þessir for the subject and þessa for the object.

These boxes are for the cardboard and the paper.
Þessir kassar eru fyrir pappann og pappírinn.
We are going to sort these bags now.
Við ætlum að flokka þessa poka núna.

Feminine: þessar

For feminine nouns like dós (can) and flaska (bottle), use þessar in both cases.

These cans and bottles go in the bin.
Þessar dósir og flöskur fara í tunnuna.
You must clean these cans for the recycling.
Þið þurfið að þrífa þessar dósir fyrir endurvinnsluna.

Neuter: þessi

For neuter nouns like glas (glass), use þessi in both cases.

Are these glasses clean?
Eru þessi glös hrein?

Talking about materials

When discussing materials in general, Icelandic commonly uses the definite article (the attached suffixes -inn, -in, -ið).

I sort the plastic, the metal and the glass together.
Ég flokka plastið, málminn og glerið saman.
The metal and the glass are clean.
Málmurinn og glerið eru hrein.