Definition from Wiktionary, the free dictionary
Alternative forms 
bas relief (plural bas reliefs)
- (sculpture) A low or mostly-flat sculpture which is carved into a wall, or is in the form of a tile mounted flat to a wall, rather than a fully three-dimensional, free-standing figure.
a low or mostly-flat sculpture
bas relief (not comparable)
- Refers to any aspect of sculpture which is flat or in the bas relief style.