The word "Trinity" comes from Latin and has a clear etymological lineage rooted in the concept of "three-ness" or a triad.

🔍 Etymology of Trinity:

• English: Trinity

  • Borrowed from:

• Old French: trinité

  • Borrowed from:

• Latin: trīnitās

  • Meaning: "triad," "threefold nature," or "the number three."

  • Derived from:

    • trīnus – meaning “threefold” or “triple”

      • A distributive form of:

        • trēs – meaning “three”

🧠 Literal Meaning:

Trinity literally means “three-ness” or “a group of three.”

🕊️ Theological Use:

• First used in a Christian theological context to refer to the doctrine of one God in three persons:
  Father, Son, and Holy Spirit.

• The term was popularized by Tertullian (c. 155–240 CE), a Latin-speaking theologian, who used Trinitas to describe this concept in Christian theology.

📘 Summary:

Word	Language	Meaning	Root
Trinity	English	Triune God, threefold	Latin trīnitās
trīnitās	Latin	Triad, threefold nature	trīnus (threefold) ← trēs (three)

The Greek equivalent of "Trinity" is Τριάς (Triás), meaning "triad" or "group of three."

Etymology of Τριάς (Triás):

• Τριάς (Triás): a feminine noun in Ancient Greek meaning “triad” or “the number three.”

  • Derived from:

    • τρεῖς (treîs) – the cardinal number “three”

    • The suffix -άς (-ás) – used to form abstract nouns.

So Τριάς literally means “a set or group of three.”

Historical/Theological Usage:

• The term Τριάς was used by early Greek-speaking Christian theologians to describe the same concept as the Latin Trinitas — one God in three persons: ὁ Πατήρ (ho Patḗr), ὁ Υἱός (ho Huiós), and τὸ Ἅγιον Πνεῦμα (to Hágion Pneûma) — the Father, Son, and Holy Spirit.

• One of the earliest known uses of Τριάς in a Christian context is by Theophilus of Antioch (2nd century CE), who wrote in Greek and referred to “the Trinity of God, His Word, and His Wisdom” (Greek: Θεός, Λόγος, Σοφία).

Summary Comparison:

Language	Word	Meaning	Root
Latin	Trinitas	Triad, Trinity	trēs (“three”) → trīnus
Greek	Τριάς (Triás)	Triad, Trinity	τρεῖς (“three”)

Both words were developed from the root for “three” and were adapted by early Christian theologians to express the doctrine of the Triune God.