Portunus

Part of speech: noun

Definitions

1. Characterized by being suitable or opportune for a particular situation or purpose
2. embodying the concept of being favorable or timely in nature
3. associated with advantageous circumstances that promote success or benefits

Etymology: Portunus was a minor Roman god whose domain was the harbor. His name comes from "portus," meaning harbor or port, and his festival, the Portunalia, was held on August 17. Later Romans also linked him to keys and doors, perhaps because harbors and gates both control passage. He is sometimes shown holding a key. The meaning you gave, favorable or timely, belongs to a different Latin word, "opportunus," the source of English "opportune." It combined "ob," meaning toward, with "portus," so it originally described a wind blowing toward the harbor, the kind a sailor needed. The sense then broadened from a favorable wind to any favorable circumstance. English likely adopted "opportune" around the 1500s.