Look up theta, Theta, Θ, or θ in Wiktionary, the free dictionary.

Theta (Θ or θ) is the eighth letter of the Greek alphabet.

Theta may also refer to:

Science and mathematics

• Θ (set theory), the least ordinal α such that there is no surjection from the reals onto α
• Theta (gastropod), a genus of sea snails
• Theta functions, special functions of several complex variables
• Theta meson, a hypothetical meson in quantum physics
• Theta representation, a particular representation of the Heisenberg group of quantum mechanics
• Theta wave, in biology
• Theta*, a pathfinding algorithm in computer science
• ${\displaystyle f=\Theta (g)}$, a Bachmann–Landau notation in computational complexity theory
• The denotation for potential temperature
• A common symbol for a variable of the measure of an angle
• SARS-CoV-2 Theta variant, one of the variants of SARS-CoV-2, the virus that causes COVID-19

Business

• GM Theta platform, an automobile platform of General Motors
• Theta Networks a telecommunications software company

Music

• Theta (musician), a Greek musician
• Theta (Brymo album), 2022

Other uses

• Theta Nedra Berwick, or simply Theta, a fictional character and the protagonist of Marvel Comics' Predator by Ed Brission
• Theta (finance), in quantitative finance, a first order derivative of an option pricing formula versus time
• Theta role, in linguistics
• Theta, Gauteng, a suburb of Johannesburg, South Africa
• An IPA symbol for voiceless dental fricative
• Tropical Storm Theta, the record-breaking 29th named storm of the 2020 Atlantic hurricane season
• Hyundai Theta engine a four cylinder gasoline engine made by Hyundai.
• Kappa Alpha Theta, a North American collegiate sorority