The Greek verb diegeirō (διεγείρω) means to fully awaken, to rouse from sleep, or to stir up completely. The prefix dia intensifies egeirō (to wake/raise), suggesting a thorough arousal from deep sleep. It appears in Matthew 1:24, Mark 4:38–39 (Jesus being awakened during the storm), John 6:18 (the sea stirred up by a great wind), and in 2 Peter 1:13 and 3:1 (Peter 'stirring up' his readers).
The most dramatic use of diegeirō is the stilling of the storm (Mark 4:38–39). The disciples diegeirō'd Jesus — they fully awakened Him — crying 'Teacher, do you not care that we are perishing?' And Jesus, fully awake, rebuked the wind and sea. The One they roused was the Lord of creation. Diegeirō in 2 Peter 1:13 and 3:1 carries a pastoral urgency: Peter stirs up his readers' memory — not informing them of new things but re-awakening their hold on what they already know. This is the ministry of reminding: the Church often does not need new truth as much as it needs to be thoroughly awakened to the truth it already holds.