Quick Definition
a leader, chief
Strong's Definition
one standing first in the ranks, i.e. a captain (champion)
Derivation: from G4413 (πρῶτος) and G2476 (ἵστημι);
KJV Usage: ringleader
Thayer's Greek Lexicon
πρωτοστάτης, πρωτοστατου, ὁ (πρῶτος and ἵστημι), properly, one who stands in the front rank, a front-rank man, (Thucydides, Xenophon, Polybius, Diodorus, Dionysius Halicarnassus, others; ὥσπερ στρατηγός πρωτοστάτης, Job_15:24); hence, a leader, chief, champion: tropically, (A. V. a ringleader) τῆς αἱρέσεως, Act_24:1-27
Mounce Concise Greek Dictionary
πρωτοστάτης prōtostatēs 1x
pr. one stationed in the first rank of an army; a leader; a chief, ringleader, Act_24:5
Abbott-Smith Greek Lexicon
πρωτοστάτης , -ου , ὁ
( < πρῶτος , ἵστημι ),
[in LXX : Job_15:24 AB * ;]
prop ., of soldiers, one who stands first, one in the front rank ( Thuc ., Xen .); hence, metaph ., a leader: Act_24:5 .†
Moulton & Milligan — Vocabulary of the Greek NT
πρωτοστάτης [page 557]
For this word which is used metaphorically of a leader in Act_24:5 , and nowhere else in the NT, see Poland Vereinswesen , p. 90.
Liddell-Scott — Intermediate Greek Lexicon
πρωτοστάτης πρωτο-στά^της, ου, ὁ, [Etym: στῆναι] "one who stands first, on the right, the right-hand man", Thuc. ; but οἱ πρ. "the front-rank men", Xen. metaph. "the leader" of a party, NTest.
STEPBible — Tyndale Abridged Greek Lexicon
πρωτοστάτης, -ου, ὁ
(πρῶτος, ἵστημι) [in LXX: Job.15:24 AB * ;]
prop., of soldiers, one who stands first, one in the front rank (Thuc., Xen.); hence, metaphorically, a leader: Act.24:5.†
(AS)