WordWeb Online

1. Understand or realize, usually after some time or initial difficulty
   - catch on [informal], get wise [informal], tumble [informal], latch on [informal], cotton on [informal], twig [Brit, informal], get it, cop on [Brit, informal]
    
2. Make contact with

Derived forms: getting onto, gets onto, got onto

Type of: apprehend, compass, comprehend, dig [informal], get the picture, grasp, grok [N. Amer, informal], savvy