Promerimnao (προμεριμνάω) means to worry or be anxious beforehand — to pre-load anxiety about future situations. It is a compound of pro (before) and merimnao (to worry/be anxious). It appears only once in the New Testament (Mark 13:11).
Mark 13:11 is the sole occurrence: 'Whenever you are arrested and brought to trial, do not worry beforehand [promerimnao] about what you will say. Just say whatever is given you at the time, for it is not you speaking, but the Holy Spirit.' Jesus here addresses the specific anxiety of pre-trial worry — the rehearsing of defenses, the anticipatory dread of interrogation. This is precisely the anxiety that promerimnao captures. The antidote is not self-preparation but Spirit-reliance. The anxiety about future moments is answered by a present promise: the Spirit will speak. This is not a prohibition against thoughtful preparation generally, but against the faithless anxiety that forgets God's promised presence.