This is the 372nd most frequent Finnish word.
kolmannen
"Kolmannen" means "of the third" in English.
The word 'kolmannen' here is a modifier for 'vaihtoehto (option)', agreeing in case with its context and specifying its ordinality as 'the third'.
Hän valitsi kolmannen vaihtoehdon.
She chose the third option.
In this sentence, 'kolmannen' serves as a genitive modifier for 'kerros (floor)', denoting possession and specifying the specific ordinal position.
Otin kuvan kolmannen kerroksen ikkunasta.
I took a picture from the third floor's window.
'Kolmannen' functions as a qualifier for 'projekti (project)', indicating that this is the third in a sequence, showing precedence.