Dictionary Definition :
Definition[1]
:
The four furnaces, or altars of the esoteric cult, each differing in shape: earth, square; water, round; fire, triangular; wind, half-moon shape.
Source
:
A Dictionary of Chinese Buddhist Terms, William Edward Soothill and Lewis Hodous
Definition[2]
:
四爐===(雜名)地(方形),水(圓形),火(三角形),風(半月形)四輪之火壇也。
Source
:
丁福保《佛學大辭典》