Definify.com

Webster 1828 Edition

Adj.

That cannot be persuaded, or influenced by motives urged.

unpersuadable ‎(comparative more unpersuadable, superlative most unpersuadable)

Not persuadable.
- 1922, Geoffrey Montagu Cookson (transl.), Prometheus Bound, page 171 in Four Plays of Aeschylus.
  For not by prayer to Zeus is access won;
  An unpersuadable heart hath Cronos' son.