This is the 508th most frequent Greek word.
τρίτο
"Τρίτο" means "third" in English.
Here 'τρίτο' is used as an ordinal number, indicating position in a sequence.
Είναι το τρίτο σπίτι από αριστερά.
It is the third house from the left.
In this sentence, 'τρίτο' functions as an adjective, describing which instance of the noun (problem) was being discussed.
Το τρίτο πρόβλημα ήταν το πιο δύσκολο.
The third problem was the hardest.
Here, 'τρίτο' refers to the order of an event or an item in a daily routine or consumption.