Where does “Twixmas” come from?

Twixmas (English) comes from English Christmas, from Middle English Cristemasse, from Old English Cristes mæsse, from Old English mæsse, from Vulgar Latin messa, from Latin missa, from Latin missum, from Latin mittō — to hurt; to exchange, remove; to replace, to...

Twixmas (English): The period in between Christmas Day and New Year, typically December 27th–31st where Boxing Day is observed, and December 26th–31st elsewhere (i.e. the first six of the Twelve Days of Christmas)

Definitions

  1. The period in between Christmas Day and New Year, typically December 27th–31st where Boxing Day is observed, and December 26th–31st elsewhere (i.e. the first six of the Twelve Days of Christmas)

Ancestry of “Twixmas”, step by step

Twixmas traces back through two separate lines of ancestry.

via English Christmas

StepLanguageWordMeaning
1EnglishChristmasA festival or holiday commemorating the birth of Jesus Christ and incorporating various Christian, pre-Christian, pagan, and secular customs including gift-giving, which in Western Christianity is celebrated on December 25 (Christmas Day) in most places
2Middle EnglishCristemasseChristmas the 25th of December
3Old EnglishCristes mæsseChristmas
4Old Englishmæssemass
5Vulgar LatinmessaEucharist, dismissal; Eucharist; dismissal;...
6LatinmissaMass; Christian eucharistic liturgy; nominative...
7Latinmissumaccusative supine of mittō; inflection of...
8Latinmittōto send, dispatch, cause to go, let go, release, discharge
9Proto-Italicmeitōto put forth, put out
10Proto-Indo-Europeanmeyth₂-to hurt; to exchange, remove; to replace, to...

via English twixt

StepLanguageWordMeaning
1Englishtwixtbetwixt, between
Every word from Proto-Indo-European meyth₂-Every word from Proto-Italic meitōEvery word from Latin mittō