This is the 288th most frequent Icelandic word.
viðkomandi
Relevant; the person/party in question.
Here, "viðkomandi" is used to mean "respective" or "concerned," referring specifically to the mentioned individual.
Viðkomandi einstaklingur hefur haft samband við okkur.
The respective individual has contacted us.
In this sentence, "viðkomandi" modifies "aðila" (party), denoting relevance or concern to the mentioned party.
Réttar upplýsingar hafa verið sendar til viðkomandi aðila.
The correct information has been sent to the relevant party.
Here, "viðkomandi" describes the noun "mál" (matter), indicating that it is the matter being referenced or addressed.