This is the 6042nd most frequent Swedish word.
jäder
"Jäder" translates to "fiber" or "tendon," though it is rarely used and might be considered archaic or regional.
Here, 'jäder' refers to 'feathers,' used to describe the plumage of a bird.
Fågelns jädrar är vackert blå.
The bird's feathers are beautifully blue.
In this sentence, 'jäder' is used colloquially to mean 'a skilled individual,' indicating proficiency in an activity.
Lennart har blivit en riktig jäder på att spela gitarr.
Lennart has become quite a whiz at playing the guitar.
This use of 'jäder' refers to the fletching of an arrow, illustrating an application in archery.