A sentinel guards against enemies getting in, so an antonym might be a mole, meaning an enemy agent operating "underground."
The address of the Sentinel Public Library is: 210 E. Main, Sentinel, 73664 3664
sentinel
Which Sentinel Primes? My guess is the Dark of the Moon one and the Transformers Animated one so I bet that the Dark of the Moon Sentinel Prime would win because the Animated Sentinel Prime is a jerk.
The Sentinel - 1996 The Sentinel by Blair Sandburg 4-8 was released on: USA: 24 May 1999
The phone number of the Sentinel Public Library is: 580-393-2244.
The sentinel watched as I passed by.
Rockhurst Sentinel was created in 1914.
The Wayne Sentinel was created in 1823.
Gundam Sentinel was created in 1987.
Catholic Sentinel was created in 1870.
The News-Sentinel was created in 1833.
Raytheon Sentinel was created in 2008.