سَرْمَدٌ

[signifies, or implies,] Continuance, or incessant continuance, (دَوَام, Kh, M, L, and اِتِّصَال, Kh, L,) of time, (Kh, M, L,) either of night or of day. (Kh, L.) [I have said “ or implies ” because I have not found it used otherwise than as an epithet, in the following senses.]

Continuing; or continuing incessantly, or endlessly; synonym دَايءِمٌ; (Zj, S, L, K;) or دَايءِمٌ لَا يَنْقَطِعُ. (Nh, L.) It is applied in this sense to night (Nh, L) [and also to day: to each in the Qur'an, 28:71 and 72]: and to night as meaning Long. (L, K.)

Accord. to El-Fakhr Er-Rázee, it is derived from السَّرْدُ, which denotes consecutiveness and uninterruptedness, and the م is added to give intensiveness to the signification: if so, its proper place is in article سرد; its measure being فَعْمَلٌ: (MF:) [thus] its م is augmentative like the م in دُلَامِصٌ. (Bd in xxviii. 71.)

One says also, هُوَ لَكَ سَرْمَدًا He, or it, is thine ever, or for ever. (Mgh in article سمد.)