It's not online but this really is the best Tagalog dictionary I've seen so far that doesn't cost over $50 or have to be split into two books. The accents and pronunciation guides will help you more than anything short of a speaking dictionary, plus it has detailed explanations for every affix (of which there are over 60). Having used this one and also checked out plenty of other ones, even those printed in the Philippines, this is your best bet. http://www.amazon.com/Tagalog-English-English-Tagalog-Standard-Dictionary-Pilipino-Inggles/dp/0781809606/ref=sr_1_1?ie=UTF8&qid=1424154596&sr=8-1&keywords=tagalog+dictionary+galvez

I am not sure if there are any. But the native Tagalog speakers here in iTalki will be willing to help you. Just post a question. :) Happy learning! :)

Have you tried checking on mobile apps (apple store or google playstore)? I saw some tagalog to tagalog dictionaries. I tried this one https://play.google.com/store/apps/details?id=appinventor.ai_pinaysabroad.Tagalog it's pretty good, although it might not have a very wide vocabulary, but having tested it, i thought it can help. If you can't find words there, you can always seek help to the netizens here on italki^^

try this link; http://www.tagalog-dictionary.com/