Sweden has a system of name days: most days on the calendar have one or more given names associated with them. Some days with fixed dates don’t have associated names; these include obvious dates such as 1 January, Nyårsdagen (New Year’s Day), and perhaps less obvious dates such as 25 March, våffeldagen (waffle day). Actually, 25 March is Marie bebådelsedag (Annunciation), previously also known as vårfrudagen (Lady Day), which was apparently misunderstood as våffeldagen. Språkrådet has a nice page about all the days in the calendar.
The list of names (namlängden; längd = list as well as length) on the Swedish calendar was substantially revised in 2001 to combine two previous lists as well as take into account changing name frequencies.
Today, 29 February, is skottdagen (leap day). The leap day was introduced with the Julian Calendar in 45BC, and originally fell on 24 February. It generally moved to 29 February sometime in the Middle Ages, but this didn’t occur in Sweden and Finland until 2000. Before this, in leap years, names associated with the days 24-28 February were shifted to the following day.
Why skott? Usually, fixed dates move forward one day of the week each year, but the effect of a leap day is to move the date forward two days, leaping over a day. In Swedish, skott commonly means a shot (from a gun), or a shoot (of a plant). Skott is related to the verb skjuta, to shoot. This verb has the present/past/supine forms skjuter/sköt/skjutit, but also forms a number of particle verbs, including skjuta in = to interpose, insert, intercalate.
Remembering the formation of the Swedish passive by adding –s, you can now translate Språkrådet’s explanation of skottdag:
Ordet skott betyder ‘något som skjutits in’
The word skott means ‘something that has been inserted’
Another nice skott phrase is this spring-appropriate expression from Norstedt’s:
skjuta skott = put forth shoots, sprout
And if you forget to send someone a message on their birthday (or name day), you should send:
Grattis i efterskott! = Belated congratulations!