Brig

Meaning: Prison; detention center.

Brig is a US military term with one of two uses:

A jail or prison on board a U.S. Navy or Coast Guard vessel.
A jail or guardhouse, especially on the premises of a U.S. military installation.

Galactica seems to have originally possessed two brigs. One has at least two small cells with bunks. The other brig has one larger cell with no commodities for high-security prisoners. In the episodes in which the brigs have made appearances, there is usually a Marine guard standing watch inside the room. In the high-security brig, there are usually around four.

After Galactica-Valerii was revealed as a Cylon, Colonel Tigh ordered a third custom-made super-reinforced brig constructed. It was built for the specific purpose of containing captured Cylon agents, who possess strength far greater than a human's, for an extended period (Resistance). The new brig was constructed with maximum security in mind; instead of having simple bars, its walls consist of metal grid screens welded tightly together, reinforced by plexiglass (a telephone is used to communicate between the inside and outside of the cell). After being brought to Galactica, Caparica-Boomer was detained within the new Cylon-brig cell. Number Six claims that Sharon's hybrid daughter will be born in this cell (Home, Part II).

Battlestar Pegasus has a more advanced brig than Galactica, with plexiglass walls instead of metal bars, and computer ID recognition cards required for entry. The Number Six copy known as Gina was ruthlessly tortured in Pegasus's brig for an extended period, before her escape.

Notable chracters who have spent time in the brig are:

Season 1

Starbuck -- striking a superior officer in the Mini-series
Aaron Doral -- under suspiscion for being a Cylon agent in the Mini-series
Specialist Socinus -- lying under oath and leaving a post in Litmus and is released in a deleted scene in Kobol's Last Gleaming, Part I
Gaius Baltar -- act of treason, allegedly collaborating with the Cylons in Six Degrees of Separation
President Laura Roslin -- consequence of a successful coup d'etat led by Commander Adama in Kobol's Last Gleaming, Part II

Season 2

Galactica-Valerii -- shooting a superior officer in "Kobol's Last Gleaming, Part II" and appearing in "Scattered".
Apollo -- mutiny in Kobol's Last Gleaming, Part II and appearing in "Scattered". He is able to be let out of the brig when on duty.
Chief Tyrol -- under suspicion of conspiring with Galactica-Sharon, in "Resistance". Also confined to the Pegasus brig by Admiral Helena Cain for killing Lt. Thorne in the process of preventing him from raping Caprica-Sharon in "Pegasus".
Cally -- for "discharging a firearm without permission" (killing Galactica-Sharonin a crowded hallway) in "Resistance" and appearing in "The Farm".
Caprica-Valerii -- Permantly detained (for being a Cylon) in the new custom-built Cylon holding cell in "Home, Part II".
Joe "Hammerhead" Palladino -- Attempted murder of a superior officer ("Final Cut")
Karl "Helo" Agathon -- Held in the Pegasus brig with Chief Tyrol by Admiral Cain for aiding in the death of Lt. Thorne, while awaiting a summary execution when Cain denied them the right to a trial by jury ("[[Pegasus (episode)|Pegasus]").
Gina -- Detained in the Pegasus brig after being discovered as a Cylon ("Pegasus"). Ruthlessly tortured and gang-raped for a long period before Dr. Baltar engineered her escape in "Resurrection Ship, Part II".
Royan Jahee -- Detained aboard Galactica on Admiral Adama's orders because of his position as leader of the Demand Peace Cylon sympathizer movement. Released after making a deal with Roslin to open a dialog while ceasing terrorist attacks ("Epiphanies").
Asha Janik -- Conducting acts of sabotage on Galactica's Viper ammunition ("Epiphanies").