deras

Etymology 1
From, from.

Adjective

 * 1)  (of rate of flow)

Etymology 3
.

Root

 * 1) the sound of something being poured.

Etymology
From, from , with the -s added in analogy with other genitive forms, specifically the masculine/neuter singular -s. Further from, genitive plural of , and ultimately from Proto-Indo-European *tóysoHom, masculine/neuter genitive plural of.

Pronoun

 * 1) their; belonging to them

Usage notes
Note the difference to sin:
 * När grannarna åker bort tar de med sig sin hund = When the neighbors travel, they bring their (own) dog.

That is, use sin if the subject of the sentence are the ones possessing something; deras otherwise.