This is the 357th most frequent Icelandic word.
fimmtudaginn
"Fimmtudaginn" means "Thursday" (accusative case) in English.
The word 'fimmtudaginn' here refers to a specific day, Thursday, highlighting it in a past context.
Ég hitti hana síðasta fimmtudaginn.
I met her last Thursday.
The word 'fimmtudaginn' here is used to indicate a future Thursday, marked clearly with the adjective 'næsta' meaning 'next'.
Við skulum hittast næsta fimmtudaginn.
We should meet next Thursday.
The word 'fimmtudaginn' is used to represent a habitual occurrence that happens on the day of Thursday.