Definitions: (1) light-hearted, buoyant, cheerful; (2) joyous and lively; happy and lighthearted; (3) exuberant; high-spirited; festive; (4) freedom from care; a contented state of mind

Derivation: Proto-Germanic, “fast, quick”

Synonyms: blithe, sprightly

• To enjoy the things we ought, and to hate the things we ought, has the greatest bearing on excellence of character. — Aristotle (384-322 bc) Greek philosopher
• The crucial task of old age is balance: keeping just well enough, just brave enough, just gay and interested and starkly honest enough to remain a sentient human being. — Florida Pier Scott-Maxwell (1883-1979) American author & playwright

Observation: A good example of how words gather multiple meanings over time.