The dictionaries try to satisfy consultants by saying, “Origin unknown,” or something of similar import.
It might be more honest to confess, “I don’t know.”
A lot of speculation by brainy men has been given, but no one knows yet whether the term hobbledehoy came into England from some other language, or whether it was an English coinage.
In fact, no one can be certain how it should be spelled, as there were some thirty different spellings used in the years following its introduction.
It was first recorded back in 1540, under the spelling hobledehoye, with the definition, “the yeres that one is neyther a man nor a boye.”
Thirty-three years later, Thomas Tusser, though recognizing the term to mean an adolescent stripling, assumed it to have a French source in the lines, from his Fiue Hundreth Pointes of Husbandrie:
The first seuen yeeres bring vp as a childe, The next to learning, for waxing too Wilde, The next keepe vnder sir hobbard de hoy, The next a man, no longer a boy.