η

η

1. (mathematics) the metric tensor in Quantum Field Theory.
2. (chemistry, physics) the coefficient of viscosity
3. (engineering) the symbol for efficiency in engineering.

• η on Wikipedia.Wikipedia

Derived from its majuscule counterpart Η, from the Phoenician letter 𐤇, heth.

η • (ē) (lowercase, uppercase Η)

1. Lower-case eta, the seventh letter of the ancient Greek alphabet. Its name was ἦτα and it represented a long open-mid front unrounded vowel: /ɛː/. It is often transliterated as either e or i. It is preceded by ζ and followed by θ.

• η' (i'), ,η (,i)
• h, H (Roman)
• и, И (Cyrillic)
• й, Й (Cyrillic)
• ⲏ, Ⲏ (Coptic)

• ἡ (hē, feminine article)
• ἥ (hḗ, feminine of pronoun ὅς) ‎
• ᾖ (êi, inflectional form of verb εἰμί)

• (Greek-script letters) Α α (A a), Β β (B b), Γ γ (G g), Δ δ (D d), Ε ε (E e), Ζ ζ (Z z), Η η (Ē ē), Θ θ (Th th), Ι ι ℩ (I i ℩), Κ κ (K k), Λ λ (L l), Μ μ (M m), Ν ν (N n), Ξ ξ (X x), Ο ο (O o), Π π (P p), Ρ ρ (R r), Σ σ ς (S s s), Τ τ (T t), Υ υ (U u), Φ φ (Ph ph), Χ χ (Kh kh), Ψ ψ (Ps ps), Ω ω (Ō ō)
• (punctuation) · ;
• (diacritics) ᾿ ῾ ´ ` ῀ ¨ ¯ ˘

• IPA^(key): /i/

From the vocalic usage of the Ancient Greek letter.

η • (i) (lowercase, uppercase Η)

1. Lower-case eta, the seventh letter of the modern Greek alphabet. Its name is ήτα and it represents a close front unrounded vowel: /i/. It is often transliterated as either e or i. It is preceded by ζ and followed by θ.

• (Greek-script letters) Α α (A a), Β β (B b), Γ γ (G g), Δ δ (D d), Ε ε (E e), Ζ ζ (Z z), Η η (Ē ē), Θ θ (Th th), Ι ι ℩ (I i ℩), Κ κ (K k), Λ λ (L l), Μ μ (M m), Ν ν (N n), Ξ ξ (X x), Ο ο (O o), Π π (P p), Ρ ρ (R r), Σ σ ς (S s s), Τ τ (T t), Υ υ (U u), Φ φ (Ph ph), Χ χ (Kh kh), Ψ ψ (Ps ps), Ω ω (Ō ō)
• (punctuation) · ;
• (diacritics) ᾿ ῾ ´ ` ῀ ¨ ¯ ˘

From Ancient Greek ἡ (hē).

η • (i) f sg

1. (definite) nominative feminine singular of ο (o) (the)