WordNet sense 1 (alert and fully informed):

knowing

WordNet sense 2 (having much knowledge or education):

informed

WordNet sense 3 (thoroughly acquainted through study or experience):

intimate, versed, intimate

WordNet sense 4 (having experience; having knowledge or skill from observation or participation):

experienced, experient

WordNet sense 5 (highly educated; having extensive information or understanding):

enlightened, learned, lettered, well-read, well-educated, learned