means The uneasy, often painful feeling that arises when you fear losing someone or something to a rival, or resent another's perceived advantage.

from From Old French 'jalousie,' built on 'jaloux' (jealous), which traces back to Late Latin 'zelosus,' meaning 'full of zeal' — and that comes ultimately from Greek 'zelos,' ardent feeling or eager rivalry. So jealousy and zeal are siblings: the same hot devotion, one pointed outward as enthusiasm, the other inward as suspicion. Curiously, English 'jealousy' and 'zeal' both descend from that single Greek root, which is also why a window blind that lets you watch unseen is called a 'jalousie.'