Lassitude: Weakness, weariness, listlessness, exhaustion, lethargy. For example, the patient complained of lassitude. From Latin lassitudo, from lassus meaning weary. From Healthy Resources 10 Rheumatoid Arthritis SymptomsHigh-Risk Myelofibrosis: Treatment Options10 Ways to Take Control of Your Migraine Featured Centers What Are the Best PsA Treatments for You?Understanding Biologics 10 Things People With Depression Wish You Knew