The Meaning of Gethsemane

Gethsemane is defined as "An instance or a place of great suffering". This makes quite a bit of sense given that Christ suffered the greatest suffering that any man has in the garden named Gethsemane. It is recounted in Matthew 26:36 that as Jesus approached the garden with his disciples he asked them to sit and watch while he went to pray. Did the disciples know what the savior was going to suffer? If they did not it made me wonder if the garden had taken the name Gethsemane before the savior had suffered there, or if the suffering defined the word Gethsemane. This helps us to understand why, perhaps, the disciples could fall asleep. If the garden was named after the suffering that occurred there then the disciples may have thought he was merely praying.