Not committed to writing; left unrecorded.

With adverbs. Not set down, forth, out, up, etc.

Not written with or as with a pen; not set down in writing.

Unmarked with letters; not containing or bearing writing.

In sense of Latin illïtterātus: Unfurnished with letters, not written upon; not expressed in words; unwritten; inarticulate. rare.

= unwritten, adj.

Unwritten.

Not subject to prescription (prescription, n.1 2); that cannot be legally taken away; = imprescriptible, adj.