"Sentry turrets" refers to small, automated devices that are designed to guard and protect a specific area or location. They are usually stationary and equipped with sensors and weapons to detect and neutralize any potential threats. Full definition
The merging of two worlds: the first Bridge Constructor ™ with an official Portal ™ license Create complex constructions in the Aperture Science labs Let GLaDOS accompany you through tricky physics adventures Use portals, aerial faith plates, propulsion gel, repulsion gel, and much more to master the complicated tasks Evade dangers such as sentry turrets, emancipation grills, laser fields, and acid (gonintendo.com)
Through each wave you are earning money to buy new guns, recruit helping soldiers, or even a portable sentry turret to deploy to obliterate all nearby enemies. (droidgamers.com)
Bagman is slotted into Rogue's backpack and can use salvage to craft ammo, health packs, and new weapons; Helm can hack into enemy computer systems and project a decoy hologram to attract enemy fire; Gunnar enhances your aim and can be converted into a handy sentry turret for added firepower. (heypoorplayer.com)