Context for Taxonomy Term Autocomplete that both completes and shows synonyms

Showing the context of an autocompleted term should be nice in any context, but if CMT (or more likely a standalone module and/or an addition to core) enables synonyms to be autocompleted, context becomes very important to prevent nonsensical results.

(See a note on this in CMT w01 status report and in an IRC chat with fago.)

For instance, "agaric" could be a synonym for "Agaric Design Collective" and the name of a separate term meaning (or a synonym for) the genus of edible mushrooms, "Agaricus". We would want autocomplete subtly displaying as much context as possible (kkaefer uses gray text below the form) to prevent tagging a client with the name of a fungus or a recipe with a web development and DJing shop. (In the community-managed taxonomy world, such broad taxonomies, and so weird results, become much more likely.) This context could include term parents (if any), term description (if any), and term synonyms (if any).

Thanks to kkaefer's enhancements of autocomplete Drupal 6 should be able to show context:

It allows modules to provide more than just one string for an autocomplete entry, allowing “rich” items. ... This allows modules to give more context when selecting an item. E.g. when a node should be selected, it’s often hard to tell from the title of the node if it’s the correct one. Additional information are often useful.

That still leaves some work to do for CMT in Drupal 5!