turris

Turris, turris, f., third declension i-stem, and one of the small group that keeps archaic alternatives alongside the regular endings: accusative turrim as well as turrem, ablative turri as well as turre. Both are correct Latin and Caesar tends to the older pair. Genitive plural is turrium.

It covers the wooden siege tower rolled up to a wall as readily as the stone tower built into one, so in a military narrative the context has to tell you which side owns it. The word travelled: Greek borrowed it, French made it tour, Spanish torre, Italian torre, and English took both tower and, through a French diminutive, turret.