1. cause to continue for a period of time, support physically/mentally, suffer injury
sustain growth/a healthy lifestyle
The verb 'sustain' means to strengthen or support over a period of time either physically or psychologically. You can say that 'Oxygen and water is needed to sustain life,' for example. You can also use the verb 'sustain' in the same way as 'to suffer' or 'to obtain' when you are talking about an unpleasant injury or something negative. You can say someone 'sustained injuries in an accident' for example. To sustain can also mean to continue for a long time without interruption, so you can 'sustain a good habit' or 'sustain a conversation'.