This is the 157th most frequent Italian word.
stessa
"Stessa" means "same" (feminine singular).
Here, 'stessa' is used as a pronoun and matches the feminine singular to refer back to the noun 'opinione' stated earlier in the sentence. It conveys that the opinion has remained unchanged.
La sua opinione è la stessa che aveva espresso prima.
Her opinion is the same as the one she expressed before.
In this sentence, 'stessa' serves as an adjective describing 'ora,' a feminine singular noun. It signifies constancy regarding the time of meeting.
Ci vediamo alla stessa ora domani.
Let's meet at the same time tomorrow.
The word 'stesso' in this sentence functions as an adjective matching the gender (masculine/feminine) and number (singular/plural) of the noun it modifies ('ristorante'). It denotes sameness in the context of the restaurant being the same location.