means Having little length, height, or duration — not stretching as far as expected in space, time, or supply.

from From Old English 'sceort,' meaning not long, with deep Germanic roots — a cousin of words tied to cutting off or shearing. The thread is appropriate: something short has, in a sense, been cut down from a fuller length. The same family likely feeds into 'shirt' and 'skirt,' garments that are essentially fabric cut short.