Pregnable

(a.) Capable of being entered, taken, or captured; expugnable; as, a pregnable fort.

Thesaurus Entries

aidless, assailable, attackable, beatable, conquerable, defenseless, expugnable, fatherless, friendless, guideless, helpless, leaderless, motherless, penetrable, surmountable, unfriended, unprotected, untenable, vincible, vulnerable, weak