"It's heavy-duty jargon that can only be defined in terms of additional jargon, given the constraint of a one-sentence definition."
"Why would the folks at OUP feel thus constrained? They'll go on and on, oftentimes, about a word common in every household, why not tell us all about a word that is not?"
Not necessarily to defend OUP, but the reason for going on and on about common words is that they have multiple definitions. The reason for stopping short on microsome is that is has only one. Whether they go on and on too much (especially on the quotations) is a separate question, but you may be conflating the OED and the COD on this one. Or I may be putting words in your mouth.
"If you truly are interested in learning a bit about ... you have questions going forward, feel free to post them."
"My concern related more to descriptive language I found lacking in understandability than to biology, but thank you for the ... for a college student, I'd think a definition of microsome, whoop-de-do, could be made understandable to a third grader even."
Actually, I don't see that that follows at all. Maybe you know something about human development that I don't?
There are lots of definitions that don't really make sense if you don't know lots of other things in the definition. Maybe that's part of the definition of jargon, in which case maybe microsome is jargon. ("Raw bits.")
"The average dictionary isn't where a specialist goes to find out about a term he probably already knows well, it is for the householder."
And dictionary makers (like all writers) have to decide on their audience. The twin ideas for an unabridged dictionary are first that, even if it takes some time, everything can be puzzled through by following through to simpler definitions, and that it's complete. I don't see how the first idea can be abandoned, so the second is the one that must be compromised for the concise version. Maybe to OUP it just means leaving out the examples, but I'm sometimes willing to settle for the general idea.
(Unfortunately for publishers of dictionaries, at times like that I almost never need to consult a dictiionary in fact, I can't recall the last time I needed to know the general sense of something and looked it up in the dictionary: I cannot possibly have been more that eight and then I would only have done it because I was required by some martinet at school.)
Jon Miller