Mid 16th century; earliest use found in Richard Morison (c1510–1556), humanist and diplomat. From classical Latin adhortātiōn-, adhortātiō persuasive speech or discourse, appeal, (in military context) speech or words of encouragement, exhortation from adhortāt-, past participial stem of adhortārī + -iō. Compare French adhortacion exhortation (mid 14th cent in an apparently isolated attestation).