incommunicable

US /ˌɪn.kəˈmjuː.nə.kə.bəl/
UK /ˌɪn.kəˈmjuː.nə.kə.bəl/
1.

An incommunicable idea cannot be expressed or explained to someone else:

:
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Their experiences of war were largely incommunicable to those at home.