Meaning of REARGUARD in English

rear ‧ guard /ˈrɪəɡɑːd $ ˈrɪrɡɑːrd/ BrE AmE noun

[ Date: 1400-1500 ; Language: Old French ; Origin: reregarde , from rere 'behind' (from Latin retro- ) + garde 'guard' ]

1 . fight a rearguard action

a) to make a determined effort to prevent a change that you think is bad, although it seems too late to stop it:

They have been fighting a rearguard action to stop a supermarket being built on the land.

b) if an army fights a rearguard action, it defends itself at the back against an enemy that is chasing it

2 . [singular] the group of soldiers who defend the back of an army against an enemy that is chasing it

Longman Dictionary of Contemporary English.      Longman - Словарь современного английского языка.