áratugi

In a sentence

• Þau hafa búið saman í áratugi.

  They have lived together for decades.

  Here, "áratugi" is used to express a time span, indicating a duration of several decades of cohabitation.

• Ísland hefur séð margar breytingar á þessum áratugum.

  Iceland has seen many changes over these decades.

  The word "áratugum" is in the dative plural case, suggesting the concept of several decades within which changes have occurred, showing temporal context.

• Áratugur er tíu ára tímabil.

  A decade is a period of ten years.

  Here, "áratugur" is the singular form, being used to define and explain the concept of a decade.