The story
Originally US English; first attested with the meaning “energy” in 1842, and with the meaning “semen” in c.1888. For semantic development, compare spunk. Perhaps ultimately from British dialect chism, chissom (“a shoot, sprout, sprig”). Unlikely to be related to Arabic جِسْم (jism, “body”) (or its derivative Hindi जिस्म (jisma)).
Etymology from Wiktionary, CC BY-SA 4.0.