This is the 793rd most frequent Icelandic word.
íþrótta
"Íþrótta" means "sports" or "of sports" in English.
Here, 'íþrótta' is the genitive plural form of 'íþrótt', relating to the involvement with or the discipline of sports.
Hann æfir íþrótta daglega.
He practices sports daily.
Here, 'íþrótta' is a possessive, describing the academy as related to sports.
Íþróttaakademían býður upp á marga námskeið.
The sports academy offers many courses.
In this sentence, 'íþrótta' is used as a compound modifier in 'íþróttaþrek' to describe the type of fitness.