Adjective
1) Not very good
2) Of moderate or low quality, value, ability or performance: ordinary, so-so
The word “mediocre” is used in Beloved by Toni Morrison on Page 58. My understanding of the word means although the carnival that Paul D, Sethe and Denver went, was a lot low in quality than the ordinary but it was an exciting and fun for them and for hundreds of colored people with the small price that they spend.
http://www.merriam-webster.com/dictionary/mediocre