What's the logical fallacy where people dismiss what you say as irrelevant to the real-world?

Quite often I see derision about ideas by people who label them as 'too academic'. Often this appears to result from laziness or an unwillingness to stretch their thinking.

What's the logical fallacy where people dismiss what you say as irrelevant to the real-world?

At its most general this is a fallacy of relevance. Precisely which one would depend on how it’s presented. If your interlocutor were to say “You’re one of them academic types, so you must be spouting nonsense” it would be ad hominem. If they said something more like “Sounds like that academic-talk, we all know how trustworthy that is.” it would be more properly categorized as an appeal to emotion, which emotion exactly would depend on the tone.

However, in order to have committed a logical fallacy they must first have been attempting to make a logical argument, i.e. they must have intended their utterance to convince someone that your argument should be discarded. They may just be arguing in bad faith.

Alternatively they are attempting to undermine the epistemic grounding of your claim by calling into question the absolute validity (or at least applicability) of (Western) philosophical logic / scientific & academic reasoning, which wouldn’t be a fallacy at all but a potentially valid tactic.

argumentum ad lapidem (appealing to the stone)

discarding the argument as absurd without giving logical reasons

Following Cerberus's suggestion above, I checked the Wikipedia List of fallacies, and found a couple that bear on the case at hand. One is the "Appeal to Poverty" or argumentum ad Lazarum:

supporting a conclusion because the arguer is poor (or refuting [it] because the arguer is wealthy).

Though this red-herring fallacy focuses narrowly on the financial status of the arguer, it could be applied metaphorically to intellectual wealth, too. Understood in terms of scholarship, the Appeal to Poverty says "I am not clever and learned like my opponent, so I can be trusted to speak plainly and honestly, free of the encrustations of pretension, sophistry, and ivory-tower bias that inevitably accompany academic learning."

A second possibly relevant fallacy is "Inflation of Conflict":

The experts of a field of knowledge disagree on a certain point, so the scholars must know nothing, and therefore the legitimacy of their entire field is put to question.

This fallacy, I've noticed, is especially popular in anti-evolution rhetoric, where disagreements about specific narrow evolutionary details serve as a basis for claiming the existence of bitter division among evolutionists over the general principles of the science.

In effect, the (broadly interpreted) Appeal to Poverty says "You can't trust an educated person," and the "Inflation of Conflict" says "Those academic types don't really know anything anyway."