What is the definition or description of: anaerobic?

With out air!: It may be in reference to organisms that grow in oxygen poor environment. Or to those that simply do not need oxygen to thrive. It is also used to refer to certain types of execises (ie weight lifting) that are short in duration but high in power out put. They are the companion (not the opposite) if aerobic exercises which are longer duration, less intense and rely on oxygen.(ie walking).