There is a list of resourceslist of resources, including dictionariesdictionaries, on English Language and Usage Meta that you may find helpful.
To answer your question about Wiktionary: as long as the definition is accurate, I wouldn't criticize or downvote an answer for citing this source. However, in general I think other dictionaries are perceived as more authoritative, so for any definition that seems like it might be controversial, I would seek another source.