uncrushable
From Longman Dictionary of Contemporary Englishuncrushableun‧crush‧a‧ble /ʌnˈkrʌʃəbəl/ adjective DETERMINEDvery determined and not easily persuaded not to do something her uncrushable will to surviveExamples from the Corpusuncrushable• Linen, we all know, crushes as easily as timid love; she looked uncrushable.• He is very keen, an uncrushable optimist.