REACT or react can be:-

• REACT (Radio Emergency Associated Communication Teams), a volunteer radio emergency service which began by monitoring CB Channel 9 radio.
• REACT belt, a restraint device.
• React Records, a 1990s London based dance record label.
• ReactOS, an open source operating system compatible with Microsoft Windows.
• React was a crust punk band from Connecticut.
• A chemical or nuclear or other process as in reaction.