The Hebrew word for fortress is mivtsar (מבצר) and it comes from the Hebrew root bitser (ב.צ.ר.) which means "to fortify". I'm not sure why you are asking for its meaning: mivtsar means "fortress" in Hebrew, but you already know that.
Another Hebrew word for fortress is metzudah (מצודה). The origin of both these Hebrew words is the Hebrew Bible (2 Samuel 5:7, and Numbers 32:36, respectively).
Perhaps you are thinking of the particular fortress near the Dead Sea called Masada. In addition to being a physical fortress, the idea of Masada connotes the heroism and martyrdom of those Jews who resisted the Roman Occupation there.
I can think of 9 translations for stronghold in Hebrew:
It is a fortress (hebrew)
It means beer. I researched Bira- it means fortress
Masada comes from the Hebrew Matzada (מצדה) which means Fortress.
He had his house locked down like a fortress.
"The soldiers defended the fortress as best they could." "The fortress was built to defend again attacks by Viking raiders." "His stoic demeanor was his fortress against the cruelty the world can inflict."
hutment
φρούριο
There is no Hebrew word for "an." There is no indefinite article in Hebrew.
The word "fortress" has two (2) syllables.1 ....... 2for - tress
Calalini is not a Hebrew word and has no meaning in Hebrew.
Masada (pronounced "matzada" in Hebrew).
In the King James version the word - fortress - appears 15 times the word - fortresses - appears twice