What is the meaning of Jealous?

Suspecting rivalry in love; troubled by worries that one might have been replaced in someone's affections; suspicious of a lover's or spouse's fidelity.

Protective; zealously guarding; careful in the protection of something (or someone) one has or appreciates, especially one's spouse or lover.

Envious; feeling resentful or angered toward someone for a perceived advantage or success, material or otherwise.

Suspecting, suspicious.

To harass or attack (somebody) out of jealousy.

To deliberately make (someone) jealous of another person's (often their partner's) associations with other people.

Source: wiktionary.org