1. Highly educated; having extensive information or understanding
   "The knowledgable professor gave a fascinating lecture";
   - knowing, knowledgeable, learned, lettered, well-educated, well-read, well-versed
    
2. Thoroughly acquainted through study or experience
   "this girl, so knowledgable with nature";
   - intimate, knowledgeable, versed
    
3. Alert and fully informed
   "surprisingly knowledgable about what was going on";
   - knowledgeable, knowing

See also: educated, experienced, experient [archaic], informed