means The liquid that can be squeezed or pressed out of fruits, vegetables, or other plant or animal tissue — and, by extension, any vital fluid or electrical/energetic power.

from From Old French 'jus,' meaning broth or liquid, which came straight from Latin 'ius' — a word that meant gravy, soup, or sauce. That same Latin root is possibly a cousin of words in Sanskrit and Old Slavic relating to broth or fermented liquid, hinting at a very old human obsession with squeezing flavor out of things. The slang senses — 'electricity,' 'gasoline,' 'influence' — are far more recent, riffing on the idea of juice as the stuff that keeps something running.