I understand what it must look like to you. I agree that this behavior is inconsistent.
The reason is that there really is a grey area here. (Actually, "dictionary definitions" is a grey area across the whole stack exchange network, and there are one or two sites which have experimentally implemented it as an official closing reason). This type of question looks indeed very basic and easily looked up. Is that bad? Well, some people seem to think yes, and some think no. Our community is heterogenous. And many of the people who stuck around and voted in August 2010 aren't around today to upvote your questions. The new ones don't remember that somebody used to upvote this kind of question back then. And also, there are some question types which were greeted with many upvotes back in the first months of the site - like the questions about favorite cookbooks - because everybody found the question interesting. Later, the community noticed that such questions don't get good answers, they just generate long me-too lists, and they get closed today by common decision. Still, some of the old questions still kick around because nobody has cared enough to look them up and close them.
So yes, this behavior is indeed inconsistent. We are doing our best to prevent this from happening (for example by documenting our decisions here on meta and by members leaving comments about how we do things here when somebody does something we don't agree with), but it doesn't work perfectly. This is indeed confusing for new members, but the democratic nature of the site (everybody can cast an up- or downvote everywhere, anonymously) has this side effect we cannot prevent completely. The definition of "on topic" changes a little bit over time because the community evolves.
What can you do as a new member? First, remember that downvotes are nothing bad or personal. They are a regulating mechanism which promotes or demotes content. This happens to everybody, I am one of the members with highest rep around here and I have had my questions closed back when I didn't know the rules well, and people continue to downvote my questions and answers. It used to bother me at the beginning, but I learned to take it in stride, because really, nobody cares how many downvotes you got. It is just a reminder that somebody disliked your question or answer. Well, you can't have everybody like everything you do.
As for close votes, the system requires that five members with sufficient rep or one moderator cast a close vote before it can be closed. This is exactly because the opinion of one member shouldn't be sufficient to close (except for mods who are elected to represent the community and are supposed to know the rules better than the average member). If somebody thought that your question doesn't fit, he may be wrong. Even if he is right and the question gets closed, this doesn't matter much to you, we are not resentful in any way. (Closing a question actually removes the rep gained from a question, so if your downvoted question gets closed, you get your rep back). Most of us are also nice enough to leave a mention as to why we cast a downvote or a close vote so that the OP can learn our rules better and/or bring counterarguments.
Which brings us to the only way questions and downvotes should concern you: you should take them as a sign to learn our rules better. In your case, you have done the right thing: first, looking around for similar cases, then asking on Meta about the inconsistency. Other things you can do is to leave a comment asking the downvoter to explain, and to ask in chat. But Meta is the most official channel, which stays here for the next wave of newbies to read long after the chat transcripts are forgotten.
A last word about the specific example you are asking about: Officially, a question being very simple (enough to be resolved with a Wikipedia lookup) is not a closing reason. I doubt that it will gather the five close votes needed, but I can reopen it if that happens. So, you can hold it there, and will probably find somebody willing to give you an answer. On the other hand, every member in the community has the right to dislike an on-topic question for whatever reason they choose, and downvote it. If the downvotes bother you, you can request the question to be closed, or deleted, and decide by yourself if you want to continue asking definition questions or not. But regardless of the downvotes, both questions are on-topic.