First off, this is my first post and I have to say that after spending hours/days reading through this site I have learned way more than I ever wanted to know...now I need more!

I have content on many of my pages that I would like make uncommon terms a link to a definition page. Typically there would be one or two of these terms per page, but could be repeated maybe 4-8 times within the article.

Example:
"Here we have content and an <a href="/category/uncommon-term.htm">uncommon term</a>...."

Would this be considered spam or bad practice? It would really help the users to understand the content better, but I don't want it to decrease my ranking.

Thanks in advance!

It would really help the users to understand the content better

That's all you need to know. Search engines don't make a practice of penalizing sites that are doing things to help their users.

Why not write a definition yourself and keep it within your website + improving page bloat and then link that page back out to the definition you are talking about.

...Typically there would be one or two of these terms per page, but could be repeated maybe 4-8 times within the article.

...Would this be considered spam or bad practice? It would really help the users to understand the content better, but I don't want it to decrease my ranking.

Linking to the uncommon term from its first usage on the page sounds like it would be helpful to your users and possibly help you on the SEO front. The "could be repeated maybe 4-8 times within the article" begins to sound spammy. I'd only link once from each article. Conceivably, you might have two or three articles on the site that might also have one link each to the definitions page.

Thanks for all the great responses! I will be writing the definitions on pages within our main website and have the first occurance of the term linked to the definitions page.

We also have several other sites that have relative content (but are category specific) and some of our main site content is syndicated to these category specific websites. Would it be wise to link the term on the category specific websites to the main site definition page, or should I make a set of definition pages for each website?

Again, thank you for all your input.

We also have several other sites that have relative content (but are category specific) and some of our main site content is syndicated to these category specific websites. Would it be wise to link the term on the category specific websites to the main site definition page, or should I make a set of definition pages for each website?

It's not wise to have your content appearing on more than one website... period... and especially not when they all belong to you.

You're much better off putting it all in one site. Google is definitely out nuking dupe content and mini-networks as we speak.

I do this often, for years and years, at my site. A good example is on this page (http://www.rustybrick.com/company_technologies.php). See all the dotted underlined words.

Usability folks love it.

And I rank in for some of those Google definitions.

rustybrick,
That's exactly what I am looking at doing. Looks great!

Now, about the content on other sites I own. The content that is syndicated is basically text ads that are related to each category and show up in a random order. Would this cause problems?

Now, about the content on other sites I own. The content that is syndicated is basically text ads that are related to each category and show up in a random order. Would this cause problems?
Think what is best for the end user.

They don't necessarily want to jump off to an external site when looking for a definition of a term on the current site. Try to keep it all internal, syndication should be fine.