impregnable
US /ɪmˈpreɡ.nə.bəl/
UK /ɪmˈpreɡ.nə.bəl/
1.
เข้มแข็ง
A building or other place that is impregnable is so strongly built and/or defended that it cannot be entered by force:
:
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Despite burglar alarms and window locks, homes are never impregnable against determined thieves.