【Dark】 , 【dim】 , 【dusky】 , 【obscure】 , 【murky】 , 【gloomy】  mean partly or wholly destitute of light.

【Dark】 , the ordinary word and the most general of these terms, implies a lack of the illumination necessary to enable one to see or to identify what is before him. It may imply lack of natural illumination (as by the sun or moon) or of artificial illumination (as by gas or electricity)  or a lack of immaterial light (as cheerfulness) or of moral or spiritual light or of brilliance—that is, the quality of lightness in color.

【Dim】 suggests just so much darkness that the things before one cannot be seen clearly or in their distinct or characteristic outlines: it may be applied equally to things viewed or to a source of illumination.

It may designate a usually bright thing that is dulled or softened or a place or time that is nearly 【dark】 .

【Dim】  as applied to eyes, sight, or insight suggests a loss of functional keenness.

【Dusky】 suggests the halfway state between light and 【dark】  characteristic of twilight: like 【dim】 it implies faintness of light but unlike that word definitely connotes grayness and an approach to darkness.

【Obscure】 is more often used in its extended senses (see 【OBSCURE】 ) than in its literal sense, but it is employed literally when there is a suggestion of darkening by covering, concealment, or overshadowing that deprives a thing of its lightness, brightness, or luster.

【Murky】 originally implied and still sometimes implies intense darkness or a darkness in which things are not even faintly visible.

In current use, the term more often suggests a thick, heavy darkness suggestive of smoke-laden fogs or of air filled with mist and dust.

【Gloomy】 (see also SULLEN) implies imperfect illumination owing to causes that interfere seriously with the radiation of light (as dense clouds or the heavy shade of many closely set trees): in addition, it often connotes pervading cheerlessness.