Finnish for "six", or, homonymously, "spruce, fir".
A common riddle says:
Joen toisella rannalla on viisi mäntyä ja toisella puolella kuusi. Kummalla puolella on enemmän puita?
(On the one bank of the river there are five pines and on the other bank has six. Which side has more trees?)
The answer is, of course, "the bank that has five pines." =)
One piece of Finnish computer jargon was "kuuslankku", for Commodore 64. 64 is literally "kuusikymmentäneljä", and six-four "kuusi-neljä". Thus, "Kuusnelonen" was common name for C64. Apparently, someone thought "kuuslankku" ("wooden board made of spruce") sounds similiar.