无间

very close / no gap between them / continuously / unbroken / hard to separate / indistinguishable

not to have / no / none / not / to lack / un- / -less

between / among / within a definite time or space / room / section of a room or lateral space between two pairs of pillars / classifier for rooms

gap / to separate / to thin out (seedlings) / to sow discontent

close relation, no gap (idiom); intimate and nothing can come between

see 阿鼻地獄|阿鼻地狱[A1 bi2 Di4 yu4]