Semantic Search and Synonyms
Synonyms (and homonyms) are really the boring basis for semantic search and I'd probably be one of the first to say that someone building semantic search shouldn't spend to much time on that because it's just not exiting enough ... but, if there where a search engine that handled this well, it would have just saved me half a day. It could have told me that what the knowledge engineering community calls knowledge formulation by "Domain Experts" and "Subject Matter Experts" is called End User Programming in the Software Engineering community. And similarly that provenance (or traceability) is Lineage in the DB community. And don't get me started about Algorithmic Debugging aka Declarative Debugging, Declarative Diagnosis, Guided Debugging, Rational Debugging aka Deductive debugging.
But then - at this level these labels are often not synonyms but similar concepts - and then it might be interesting again. The query "Similarity based semantic search" still returns nothing ;-)