Semantic Dictionary

One of my "unfinished businesses" is a semantic dictionary. Basically it will be a gigantic database of all words in all forms (as entities) and they'll have a set of attributes and relations between them, defining what kind of word it is (subject, verb...) and what relations between other words are (synonym, antonym, the same word in different language...).

I expect the primary usage in semantic search. The search engine will use some kind of universal meta language, to which all queries in natural languages will be transformed.

I can't say how (and if) it will work exactly, it's just a thing I've been thinking of quite a long time. I'm aware there are some nuances and pickles (like the same word with different meaning not only in different languages) or how to deal with phrases in search queries (my former thought was just to analyse word by word, but It's not that easy).

These are some of expected unknowns I didn't make any further research about and therefore I don't have comprehensive overview of it.

And, last, but not least, it will be a nice performance test :)