Authentical

Origin

From authentic + -al.

Full definition of authentical

Adjective

1. (archaic) Authentic.
• 1596, Edmund Spenser, The Faerie Queene, IV.12:He graunted it: and streight his warrant made,
  Under the Sea-gods seale autenticall ….
• 1603, John Florio, translating Michel de Montaigne, Essays, II.33:The curious and exact care he had of his body, is an authenticall witnesse of it, forsomuch as he used the most lascivious meanes that then were in use ....