The Greek arketos (ἀρκετός) means 'sufficient,' 'enough,' or 'adequate.' It appears in Matthew 6:34 ('sufficient for the day is its own trouble'), Matthew 10:25 ('it is enough for a disciple to be like his teacher'), and 1 Peter 4:3 ('the past is sufficient time for doing what pagans choose to do'). The word marks the boundary of adequacy — neither too much nor too little.
Jesus uses arketos in Matthew 6:34 to reorient human anxiety: 'Do not worry about tomorrow... sufficient for the day is its own evil.' The disciple does not need to import tomorrow's problems into today. God's provision comes in portions — daily bread, not weekly stockpiles — because arketos by day teaches daily dependence on the Father. In Matthew 10:25, Jesus reframes the disciple's expectation: if they called the master Beelzebul, it is arketos (sufficient, expected) that they will do the same to the disciples. Suffering is not a surprise; it is adequate evidence that we belong to Christ. In 1 Peter 4:3, the old life is arketos — it has had enough time. Grace draws a line and says: 'That was then. This is now.'