In the FAQ for this straight dope site I noted this reference:
Could you explain the term “feckless youth” and perhaps provide a more useful example and a bit of history on the term “feckless” beyond the obviously slanderous reference?
I recall it as a rather old world term meaning “indentured youth” modernized now as a tongue in cheek “non commissioned intern” or perhaps “commandeered child”.
Care to comment?
Huh? AFAIK it just means something along the lines of happy-go-lucky, careless, irresponsible or summat. Are you remembering the right word?
etc.
I think my recall fits it well.
I’m thinking 1800’s or earlier. Possibly European or English usage. It’s a term that has a rather diverse etiology, not all of which is available online.
How about “Capybara”? Now there’s a term…
Isn’t that a pig-mouse?
Marsupial or avunclark-pygmy?
No, not avuncular. Probably need a reference library for that one. I think the capybara is an avunclark-pygmy.
-Tom
Virtually every word in the English language has shifted or added meanings over its lifetime. That a word originally meant one thing is totally irrelevant today.
However, etiology still has a single primary usage as the cause or origin of disease, not causation or origin in general. The word when applied to language is etymology.
I have quite a sore throat these days. I wonder what may be its etymology. 
Feckless is in the 1913 version of Webster’s Revised Unabridged Dictionary, but not the 1828 edition.
According to 1000 Most Obscure Words by Norman W. Schur, the term “feckful”, meaning “strong and brawny” is listed in Robert Willan’s List of Ancient Words at Present Used in the Mountainous District of the West Riding of Yorkshire, which dates from 1811. The original root of both feckless and feckful is “feck”, a mainly Scottish and Northern English term that in turn seems to be a variant of “effect”, having lost its unstressed initial vowel.