From the same as pselaphao; a pebble (as worn smooth by handling), i.e. (by implication, of use as a counter or ballot) a verdict (of acquittal) or ticket (of admission); a vote -- stone, voice.
see GREEK pselaphao
1. since in the ancient courts of justice the accused were condemned by black pebbles and acquitted by white (cf. Passow, under the word, ψῆφος, 2 c, vol. ii, p. 2574b; (Liddell and Scott, under the word, 4 d.); Ovid. met. 15, 41; (Plutarch, Alcib. 22, 2)), and a man on his acquittal was spoken of as νικησας (Theophrastus, char. 17 (19), 3) and the ψῆφος acquitting Dim called νικητήριος (Heliodorus 3, 3 under the end), Christ promises that to the one who has gained eternal life by coming off conqueror over temptation (τῷ νικουντι (A. V. to him that overcometh)) he will give ψῆφον λευκήν, Revelation 2:17; but the figure is explained differently by different interpretations; cf. Düsterdieck (or Lee in the 'Speaker's Commentary') at the passage; (B. D. under the word, Stones, 8). Ewald (Die Johann. Schriften, ii., p. 136; (cf. Lee as above; Plumptre in B. D. under the word, Hospitality, at the end)) understnads it to be the tessera hospitalis (cf. Rich, Dict. of Antiq., under the word, Tessera, 3; Becker, Charicles, namely, i. note 17), which on being shown secures admission to the enjoyment of the heavenly manna; the Greek name, however, for this tessera, is not ψῆφος, but σύμβολον.
2. a vote (on account of the use of pebbles in voting): καταφέρω (which see), Acts 26:10.