Vine's Expository Dictionary: View Entry
φύλαξ phýlax, foo'-lax; from G5442; a watcher or sentry:—keeper.
The KJV translates Strong's G5441 in the following manner: keeper (3x).
a guard, keeper
Strong's Number G5441 matches the Greek φύλαξ (phylax), which occurs 3 times in 3 verses in the TR Greek.
View OT results in the LXX Greek concordance
View NT results in the MGNT Greek concordance
Act 5:23
Act 12:6
Act 12:19