What is the meaning of plenitude? Definition of plenitude 1 : the quality or state of being full : completeness 2 : a great sufficiency : abundanceWhat are the side effects of plenity? The overall incidence of side effects with Plenity was no different than placebo. The most common side effects were diarrhea, distended abdomen, infrequent bowel movements, and flatulence. Contact a doctor right away if problems occur.How much does plenity cost? Start your online consultation now with a doctor who can prescribe Plenity, if it’s appropriate for you. $1.75 per meal. Prescription required. Plenity is an aid for weight management in adults who are overweight or obese and have a body mass index (BMI) of 25 to 40 kg/m 2, when combined with diet and exercise.Do i need a prescription for plenity? Prescription required. Plenity is an aid for weight management in adults who are overweight or obese and have a body mass index (BMI) of 25 to 40 kg/m 2, when combined with diet and exercise. New Look Coming Soon!