Plemmyra (πλημμύρα) means a flood, a rising of water, or high tide. It describes the overwhelming force of rising waters — specifically a river in flood stage. In its sole NT occurrence, Jesus uses it in the parable of the two builders.
In Luke 6:48, Jesus describes the wise builder whose house withstands the flood: 'When a flood came, the torrent struck that house but could not shake it.' The plemmyra represents the inevitable trials that come upon every life. Jesus does not promise believers will avoid the flood — He promises they will survive it. The difference is not the severity of the storm but the foundation. This parable closes the Sermon on the Plain as Jesus' most urgent appeal: hearing His words is not enough — they must be put into practice.