be hardened; be experienced, know well
Latin word, found 90 times in the texts on Socratos.
Cicero, Letters to his Friends 4.5.2: … omnis. hoc uno incommodo addito quid ad dolorem adiungi potuit? aut qui non in illis rebus exercitatus animus callere iam debet atque omnia minoris existimare? an illius vicem, cedo, doles?
Vergil, Aeneid 4.405: convectant calle angusto; pars grandia trudunt
Ovid, Metamorphoses 2.824: labitur, et callent amisso sanguine venae.
All forms of calleo