Assuming that it is a polygon, or a shape with closed sides, a 14-sided shape is called a tetradecagon or a tetrakaidecagon. Any polygon could also be called an n-gon, where n is the number of sides. Here, a 14-sided shape would be a 14-gon.
Names exist for polygons with nearly any number of sides. These names are constructed by combining the Greek prefix and suffix for the number of sides. For instance, the prefix for 70 is "heptacontakai" and the suffix for two is "digon." Therefore, the word for a 72-sided polygon would be heptacontakaidigon. Using the n-gon naming system instead, a 72-sided polygon would be a 72-gon.