Definition of sustain

• lengthen or extend in duration or space; "We sustained the diplomatic negotiations as long as possible"; "prolong the treatment of the patient"; "keep up the good work"
• undergo (as of injuries and illnesses); "She suffered a fracture in the accident"; "He had an insulin shock after eating three candy bars"; "She got a bruise on her leg"; "He got his arm broken in the scuffle"
• provide with nourishment; "We sustained ourselves on bread and water"; "This kind of food is not nourishing for young children"