unattackable
unat·tac·kable
adjective
1.
- “an impregnable fortress”
- “fortifications that made the frontier inviolable”
Origin
From un- + attack + -able.
WordNet 2.1 (Princeton University). Wiktionary (CC BY-SA). WordNet 2.1 Copyright Princeton University. All rights reserved. Wiktionary content is available under the Creative Commons Attribution-ShareAlike Licence.