Douglas Harper's Etymology Dictionary
1880, from Latinized form of Greek ephebikos "of or for an ephebe," from ephebos "one arrived at puberty, one of age 18-20," from epi "upon" (see epi-) + hebe "early manhood," from PIE *yegw-a- "power, youth, strength." In classical Athens, a youth of 18 underwent his dokimasia, had his hair cut off, and was enrolled as a citizen. His chief occupation for the next two years was garrison duty.
Wiktionary
a. 1 youthful 2 (context medicine English) pubescent, adolescent
Usage examples of "ephebic".
LSD, as a relatively ephebic and clueless organic chemist, while futzing around with ergotic fungi on rye.
Employee parking lot, from which dumpsters Pemulis will then get Mario In-candenza and some of the naïver of the original ephebic urine-donators themselves to remove, sterilize, and rebox the bottles under the guise of a rousing game of Who-Can-Find,-Boil,-And-Box-The-Most-Empty-Visine-Bottles-In-A-Three-Hour-Period-Without-Any-Kind-Of-Authority-Figure-Knowing-What-You're-Up-To, a game which Mario had found thumpingly weird when Pemulis introduced him to it three years ago, but which Mario's really come to look forward to, since he's found he has a real sort of mystical intuitive knack for finding Visine bottles in the sedimentary layers of packed dumpsters, and always seems to win hands-down, and if you're poor old Mario Incandenza you take your competitive strokes where you can find them.