diligence, guard, office, prison, ward, watch

Boyd’s Bible Dictionary:

(seizing). Ward or lock-up (Lev. 24:12; Num. 15:34); well or pit (Gen. 37:24; Jer. 38:6-11); part of a palace (2 Chron. 16:10; Jer. 32:2; Acts 23:10,35).

Concise Bible Dictionary:

In Egypt, in Babylon, among the Romans, and doubtless in most other nations, these were used as places in which to secure prisoners. Joseph was cast into prison, and his feet were hurt with fetters (Psa. 105:18), though it does not appear that there was any trial as to the crime of which he was accused. God interfered on his behalf, and made the keeper or jailor favorable to him, and he committed all the prisoners into Joseph’s care. This was the royal prison, but the condition of the place is not known: he called it “the dungeon.”
Jeremiah was confined in “the court of the prison,” a place to which the Jews could come and where they could converse with him (Jer. 32:2-12). Jehoiachin was in prison in Babylon (Jer. 52:31). The prison at Jerusalem, under the Romans, is more fully described. Peter was bound by two chains, and lay asleep between two soldiers. It was under military rule, and the soldiers were responsible for the safety of the prisoners. The angel conducted Peter through the first and second guard to the outer iron gate that led into the city. This shows what is meant by the “inner prison” mentioned elsewhere (Acts 12). At Philippi there was a jailor who was responsible for the safety of the prisoners. He, supposing some had escaped, was about to destroy himself, when Paul stopped him (Acts 16:23-27).
Fallen angels are said to be kept in “everlasting chains” (Jude 6); and there are spirits which are kept in prison (1 Peter 3:19). The abyss in which Satan is to be shut up for the thousand years is also called a prison, which may refer to the same place (Rev. 20:7).

Strong’s Dictionary of Hebrew Words:

Transliteration:
mishmar
Phonic:
mish-mawr’
Meaning:
from 8104; a guard (the man, the post or the prison); a deposit (fig.); also (as observed) a usage (abstr.), or an example (concr.)
KJV Usage:
diligence, guard, office, prison, ward, watch