Origin: Germanic Old English prefix
Beside has 2 different meanings across 1 category:
Otherwise; else; besides.
"I do not want to argue, and beside that, I am too tired to continue."
Next to; at the side of.
"The tall oak tree stood beside the old stone cottage, casting a cool shadow over its front porch."
From Middle English beside, besiden, bisyde (also besides > besides), from Old English be sīdan, bī sīdan ("by the side (of), on the side (of)"). Compare Saterland Frisian biesiede ("aside"), German Low German bisied ("aside"), German beiseite ("aside, to one side"). Compare also Dutch terzijde ("aside"). By surface analysis, be- + side.