be dark, be gloomy, be pitch-black

It (the night) was, or became, black; (TA;) or intensely dark: (Mgh:) and اِدْلَأَمَّ signifies the same; (K and TA in art. دلم;) the ء being a substitute for ه. (TA in that art.) And It (darkness) was, or became, dense, or thick. (K.) See the next paragraph. ― -b2- Also He (a man) was, or became, aged; and so اِدْلَهَنَّ. (K in art. دلهن.)

Dark. (K.) You say لَيْلٌ دَلْهَمٌ Dark night: (TA:) and ↓ لَيْلَةٌ مُدْلَهِمَّةٌ A dark night. (S, TA.) ― -b2- And Deprived of his reason by love: (K:) a signification which shows the م to be augmentative; for it is from الدَّلَهُ: or, accord. to IKtt and others, the ل in ↓ ادلهمّ is augmentative; for, they say, it is from الدُّهْمَةُ: either opinion is allowable. (TA.) ― -b3- Also The wolf. (K.) ― -b4- And The male of [the bird called] the قَطَا [like دَيْلَمٌ]. (K.)

A man who is penetrating, sharp, vigorous, and effective. (K.) ― -b2- And A lion. (K.)

Densely black. (TA.) And أَسْوَدُ مُدْلَهِمٌ Intensely black. (Lh, K.) See also دَلْهَمٌ. ― -b2- فَلَاةٌ مُدْلَهِمَّةٌ [A desert, or waterless desert,] in which are no signs of the way. (TA.)