áhrifaríkum
The term "áhrifaríkum" is an adjective in the Icelandic language. It translates directly to "influential" or "impactful" in English. It is used to describe a person, thing, event, or idea that has a significant effect or power to cause change. The word is the dative plural form of the adjective "áhrifaríkur" which means influential. Therefore, "áhrifaríkum" specifically refers to multiple entities that are influential.
For example, one might say "þessir þættir voru áhrifaríkum í ákvörðun sinni" which translates to "these factors