What does that mean???

I consider myself to be pretty smart but at times I feel dumb. Those times are usually when my girlfriend or someone I know uses a word and I don't know what it means. So, I decided I needed to do something about it. I know some people that are doing 365 days of self portraits and i thought I could do similar. I don't have a camera to do that but I do have a dictionary. So, I decided I would start learning a new word a day. So far the words are mirth and arrears. If anyone has any good words for me let me know. I am setting this as one of my resolutions this year. I feel this is going to be the year of even more new and exciting things.