This is the 389th most frequent Icelandic word.
stór
"Stór" means "big" or "large" in English.
Here, 'stórt' is the neuter singular nominative form and describes the size of the house, which is a neuter noun in Icelandic.
Húsið er mjög stórt.
The house is very big.
In this sentence, 'stórt' is also the neuter form and is used metaphorically to indicate significant or great value.
Bókin hefur stórt gildi.
The book has great value.
'Stór' in this context describes a significant or important event, showing its use to indicate importance.