Noun
English Wikipedia has an article on:December solsticeWikipedia
December solstice (usually uncountable, plural December solstices)
(astronomy) The moment when the sun reaches the southernmost point of the sky, occurring on December 21–22. That would be winter solstice in the northern hemisphere and summer solstice in the southern hemisphere.
Finally, the December solstice occurs on day 21 of this month. Source: Internet