How do nurses communicate with patients who are seriously ill and their families? How do nurses use language and how does this help patients and families to create and understand their actual and future possible lived realities? Nowhere is communication more essential to nursing praxis than when a patient’s lived reality is under threat with advancing, advanced or serious, terminal or critical illness and who may be deemed at-end-of-life. While nurses speak these words, underlying assumptions associated with the terms may be unarticulated. Yet it is commonly assumed that patients and families understand these and the plethora of other medical terms that have evolved to become what I will term, the serious illness lexicon. In this paper the language of serious illness – arguably its own lingua franca, will be explored, critiqued and questioned using a philosophical lens. For this, I turn to Ludwig Wittgenstein, the pre-eminent philosopher of language who coined the notion of language games. For Wittgenstein, language and its concepts were instruments that were learned, practiced and woven into a whole – a language game- that was dependent on rules of which one may be conscious or not. I propose that the idea of the language game can illuminate what has largely been the unexamined creation, selection and use of language in efforts to improve communication in the care of the seriously ill. Using Wittgenstein’s ideas, the language of care for the seriously ill will be considered, examples of the nature and dynamics of language games in serious illness offered and their assumptions and rules examined within various contexts. Finally, issues arising about Wittgenstein’s conception of language games will be considered.