1. any of the intervals into which a numerical expression of the taper (of a tree stem or log) may be divided for classification or use, i.e., commonly a range of form factors, form quotients, or form-point heights 2. the actual trees or logs falling into such an interval 3. historically, Girard form class, a form quotient computed as the ratio between stem diameter inside bark at the top of the first log divided by DBH multiplied by 100 This definition last updated 10/24/2008