proskartereō

προσκαρτερέω combines the preposition προς ("toward") with καρτερέω ("to endure, hold out"), itself from καρτερός ("strong"), yielding a core sense of strength directed at an object and sustained over time. In Koine it was a workaday term for steadfast presence: Polybius and Josephus use it of troops persisting in a siege, Demosthenes of servant-girls attending a mistress, and documentary papyri of officials keeping to a post or tenants sticking to their land (Moulton-Milligan; Spicq). The Septuagint has it twice, at Numbers 13:20 (rendering a Hebrew call to be strong) and Susanna 6 (constant presence at a house). In the New Testament it occurs ten times, six of them with prayer, and in Luke and Paul it becomes near-technical for the settled corporate devotion of the early church (Grundmann, TDNT). The lexica organize the verb by its construction rather than by unrelated senses: with a thing or activity it means to devote oneself to or persist in (Acts 2:42; Romans 12:12; Colossians 4:2); with a person, to attend upon or attach oneself to (Acts 8:13; 10:7); with a place, to remain constantly there (Acts 2:46); with an inanimate subject, to be kept ready (Mark 3:9); and in Romans 13:6, of magistrates devoting themselves to their office. Scholars differ chiefly on taxonomy (BDAG groups three senses, LSJ four, Louw-Nida spreads it across three semantic domains) and on emphasis (habitual constancy versus effortful tenacity), while agreeing on the unified core. The cognate noun προσκαρτέρησις appears once, at Ephesians 6:18.