time - Does Japanese have short versions of weekdays?

Like in English we could type the days of the week as "Sun, Mon, Tue, Wed, Thu, Fri, Sat."

Does Japanese have shortenings for weekdays? Like:

日,月, 火, 水, 木, 金, 土

Instead of:

日曜日, 月曜日, 火曜日, 水曜日, 木曜日, 金曜日, 土曜日

Or:

にち, げつ, か, すい, もく,きん, ど

Instead of:

にちようび, げつようび, かようび, すいようび, もくようび, きんようび, どようび

Or do the short versions not make sense?

Answer

Yes. You can address any day of the week by its first kanji, and you can refer to it in short using the respective onyomi. For example, you can say 月{げつ}水{すい}金{きん}はお休みです。 In fact you often hear the weekend referred to as (きん)どにち. You can also go half way and abbreviate it just to ◯曜, as in 日曜.

Outside of spoken language you see the kanji used to represent days of the week all the time, so you might see on a poster something like ８月５日（月）. Other abbreviations that you might see that are related to the day of the week are 休 (when somewhere is closed), 祝 (for holidays), 平 (for weekdays), and probably some others.