1) Young Greek citizen 2) Young man of ancient Greece 
[personal name] As well as being a general epithet, Ephebus (ancient Greek - adolescent) often occurs as an individual name, as in the cases of: ...
in ancient Greece, any male who had attained the age of puberty. In Athens it acquired a technical sense, referring to young men aged 18–20. From ... [1 related articles]
ephebus A citizen between eighteen and twenty years. From Greek history, a youth, through Latin (epi + hebe) youth, early manhood.
a youth of ancient Greece just entering manhood or commencing training for full Athenian citizenship.