The name given by the Dúnedain to the second month of the year. The name Nínui comes from the Sindarin language, and its Quenya equivalent is Nénimë. Both these names seem to be related to the Elvish stem nen, relating to water and wetness. In one case, indeed, the word Nínui is translated as 'tears', but used as a month-name it is presumably a reference to the rain showers of late winter.
The rainy month of Nínui was directly equivalent to the month named Solmath on the Shire Calendar, and ran on a modern calendar from 22 January to 20 February. It was preceded by Narwain, the first month of the year, and succeeded by the third month, Gwaeron. In Middle-earth, Nínui was seen as the lessening of the worst colds of winter, and its end marked the point when long journeys could be undertaken (which was usually avoided during the worst of the winter weather).