SOMBRE is validvalid

somber [adj SOMBRER, SOMBREST] : SOMBRELY [adv], SOMBRENESS [n]

28,483 of 196,601 in NWL2023·also valid in CSW24

gloomy, dark [adj SOMBRER, SOMBREST, SOMBRELY] / to make sombre [v SOMBRED, SOMBRING, SOMBRES]