1.technology used in mobile phones before 4G or 5G that made it possible to use the internet, watch video, etc. 3G is short for "third generation"
3G came along in 2003 and made it possible to browse web pages, make video calls and download music and video on the move.
They invested heavily in 3G mobile phone networks.
2.abbreviation for third-generation: relating to or using a technology that gives mobile phone and computer users a high-speed internet connection as well as good video and other advanced features
a 3G network
3G phone/technology/service