This is the 546th most frequent Slovenian word.
starosti
"Starosti" in Slovenian means "ages" or "elderly" depending on context.
Here, 'starosti' is used in the genitive plural form to indicate a range of ages.
Otroci različnih starosti se igrajo skupaj.
Children of different ages play together.
In this sentence, 'starosti' is used in the locative singular form to denote a specific age at which something happens.
V starosti petdeset let je začela študirati slikarstvo.
At the age of fifty, she started studying painting.
'Starosti' here is in the locative singular form, referring to a specific age in life being discussed.