hard chancre [AS, heard + Fr, canker] , a syphilitic chancre or primary lesion that develops at the site of a syphilis infection. The lesion begins as a small red papule that gradually hardens and erodes into an extremely contagious, although painless, ulcer. A secretion exuded by the sore contains Treponema pallidum, the organism that is the causative agent of syphilis in humans.
