Improve dictionary's internal linking structure

What I want to achieve:

I have an online dictionary which works quite fine - but the crawling by search engines (especially Google) could be better.

So I would like to improve the internal linking structure on my website so that Google can easily find (almost) all pages of the dictionary.

What I know yet:

The number of internal links per page should not exceed 100. Search engines don't like pages containing masses of links - looks spammy. And a website is not to be designed for search engines but for the users. So the usability should not suffer from this optimization, best case would be if the usability does even increase.

My ideas for improving the internal linking structure so far:

on each dictionary entry page: link 25 similar words which could be mixed up
create an index: list of all dictionary entries (75 per page)
...

Can you help me to optimize the linking structure?

Thank you very much in advance!

Solution

You could link to synonyms and antonyms, which would be both user-friendly and crawler-friendly. But I think the biggest thing you could do to improve crawling, particularly by Google, would be to add a sitemap:

Sitemaps are an easy way for webmasters to inform search engines about pages on their sites that are available for crawling. In its simplest form, a Sitemap is an XML file that lists URLs for a site along with additional metadata about each URL (when it was last updated, how often it usually changes, and how important it is, relative to other URLs in the site) so that search engines can more intelligently crawl the site.

Google has lots of information on Sitemaps and how to generate them on their webmaster help pages.