The story
From ski + bike (“bicycle”). From being akin to a bicycle with skis in place of wheels.
Etymology from Wiktionary, CC BY-SA 4.0.
skibike
Today it means: An analogue to a bicycle for downhill skiing, which has a frame similar to a bicycle's and with wheels replaced by skis, which may or may not include a seat, and may or may not include pegs in place of pedals (without pegs, one would stand on the rear ski). Full definition →