1630s, "one who enforces order;" see discipline; it was earlier used (often with capital D-) of Puritans who wanted to establish the Presbyterian "discipline" in England (1580s). An earlier word in the sense "enforcer of discipline" was discipliner (mid-15c.). Meaning "advocate of greater discipline" is from 1746.
dischargeable
disciple
discipleship
disciplinable
disciplinant
disciplinarian
disciplinary
discipline
disclaim
disclaimer
disclose