Tupplur means 'nap', or a short period of sleep, usually taken during daytime, and you'll usually hear it used in the phrase ta en tupplur (to take/have a nap). It's a compound noun, made up of two different words: tupp + lur.
Lur on its own can be used to mean 'nap' or 'doze', although it also has several other meanings. It can mean 'bell' or 'horn', while the set phrase på lur means something like 'on the lookout' or 'in wait'.
The strange part of tupplur is tupp, which means 'cock' – in the sense of a male chicken.
According to the word experts at the Swedish Language Council, the term comes from the fact that chickens tend to sleep in short periods, often while standing. An earlier Swedish word for nap, in fact, was hönssömn, literally meaning 'chicken sleep', and similar nouns are found in Norwegian (høneblund), Danish (hønsesøvn) and Icelandic (hænublundur).
Tupplur is believed to date back to at least the early 1800s, and is a common word in Swedish. It's not that surprising if you consider that the Nordic nations were agricultural economies for much longer than many other European countries. In English, meanwhile, the usual animal-inspired term for a short sleep is 'cat nap', based on the fact that cats often doze for just a few minutes at a time, although in total they sleep far more than chickens.
If you're looking for more poultry-themed idioms, the Swedish language has a plentiful supply: early-risers might say they're uppe med tuppen (up with the cockerel), and one way of describing someone with a big ego is to say they're stolt som en tupp (proud as a rooster).
In Swedish, you'll also hear the direct English loan word powernap (all one word) used to refer to especially short snoozes, and the direct translation kraftlur is also sometimes used in spoken or online Swedish. By the way, 'snooze' has also been borrowed into Swedish as the verb snooza, but it refers specifically to pressing the 'snooze' button on an alarm clock.
Jag är jättetrött, jag måste ta en tupplur och sen en kopp kaffe
I'm really tired, I need to take a nap and then have a cup of coffee
Är det ok att ta en tupplur på jobbet?
Is it OK to take a nap at work?