siding

Etymology 1

side + -ing (“material, collection”).

noun

1. (Canada, US) A building material which covers and protects the sides of a house or other building.
   Ugh. If there's one thing I can't stand it's cheesy vinyl siding.

Etymology 2

verb

1. present participle and gerund of side
   Whenever he hears an argument, he can't help siding with one party or the other.

Etymology 3

side + -ing (“derivative noun, having the quality of”).

noun

1. (rail transport) A second, relatively short length of track just to the side of a railroad track, joined to the main track by switches at one or both ends, used either for loading or unloading freight, storing trains or other rail vehicles; or to allow two trains on a same track to meet (opposite directions) or pass (same direction) (the latter sense is probably an American definition).
   Laid out over six square kilometres, Sellafield is like a small town, with nearly a thousand buildings, its own roads and even a rail siding – all owned by the government, and requiring security clearance to visit. December 15 2022, Samanth Subramanian, “Dismantling Sellafield: the epic task of shutting down a nuclear site”, in The Guardian