Theta

Greek alphabet
Α α Alpha	Β β Beta
Γ γ Gamma	Δ δ Delta
Ε ε Epsilon	Ζ ζ Zeta
Η η Eta	Θ θ Theta
Ι ι Iota	Κ κ Kappa
Λ λ Lambda	Μ μ Mu
Ν ν Nu	Ξ ξ Xi
Ο ο Omicron	Π π Pi
Ρ ρ Rho	Σ σ Sigma
Τ τ Tau	Υ υ Upsilon
Φ φ Phi	Χ χ Chi
Ψ ψ Psi	Ω ω Omega
obsolete letters
Ϝ ϝ Digamma	Ϻ ϻ San
Ϙ ϙ Qoppa	Ϡ ϡ Sampi

Note: A theta probe is a device for measuring soil moisture

Theta (upper case Θ, lower case θ) is the eighth letter of the Greek alphabet. In the system of Greek numerals it has a value of 9.

The lower-case letter θ is used as a symbol for:

A plane angle in geometry.
θ is the voiceless (inter)dental fricative in the International Phonetic Alphabet.

The upper-case letter Θ is used as a symbol for:

Earth Day
Death
Diminsionless Temperature in transport phenomena

The letter Θ is an abbreviation for the Greek word thanatos (θάνατος: "death"; see Thanatos and Thanatology) and as it vaguely resembles a human skull, was occasionally used by Greeks as a warning symbol for death, in much the same way that skull and crossbones are used today.

The Cyrillic letter Fita arose from Theta.

Categories: Greek letters