Adjective
(philosophy) Not capable of being said.
(rare) Not allowed or not fit to be said.
Source: en.wiktionary.orgMuch of philosophy involves attempts to say the unsayable: "What we can say at all can be said clearly," he argues. Source: Internet
The main contention of such readings is that Wittgenstein in the Tractatus does not provide a theoretical account of language that relegates ethics and philosophy to a mystical realm of the unsayable. Source: Internet