This is the 52nd most frequent Romanian word.
cea
"CEA" is the feminine singular definite article in Romanian, meaning "the."
The word 'cea' is used here as a superlative marker meaning 'the most' in combination with an adjective.
Aceasta este cea mai interesantă carte pe care am citit-o.
This is the most interesting book I have read.
Here, 'cea' functions as a definite article introducing a specific attribute, distinguishing the subject among others.
Fata cea mică este mereu veselă.
The youngest girl is always cheerful.
In this case, 'cea' acts as a demonstrative pronoun referring to a specific person mentioned previously in context.