Noah Webster's New International Dictionary of the English Language

1. (a.) Zealous; solicitous; vigilant; anxiously watchful.

2. (a.) Apprehensive; anxious; suspiciously watchful.

3. (a.) Exacting exclusive devotion; intolerant of rivalry.

4. (a.) Disposed to suspect rivalry in matters of interest and affection; apprehensive regarding the motives of possible rivals, or the fidelity of friends; distrustful; having morbid fear of rivalry in love or preference given to another; painfully suspicious of the faithfulness of husband, wife, or lover.