Now it seems the youngsters have been held in a concretebunker all this time.
Times, Sunday Times (2015)
Since then Ukraine has reinforced the port's defences, building concretebunkers along the northern approach roads and fortified checkpoints inside the city.
Times, Sunday Times (2015)
Definition of 'bunker'
bunker
(bʌŋkəʳ)Explore 'bunker' in the dictionary
countable noun
A bunker is a place, usually underground, that has been built with strong walls to protect it against heavy gunfire and bombing.
Definition of 'concrete'
concrete
(kɒŋkriːt)Explore 'concrete' in the dictionary
uncountable noun [oft NOUN noun]
Concrete is a substance used for building which is made by mixing together cement, sand, small stones, and water.