(US, colloquial) A member of the Kappa Alpha Theta sorority.

The eighth letter of the Modern Greek alphabet, ninth in Old Greek: Θ, θ.

(mathematics) The measure of an angle.

(aviation, by extension) Pitch angle; the angle between an aircraft's longitudinal axis and the horizontal plane.

(finance) The sensitivity of the value of a derivative with respect to time; the "time decay".

(biology) Designating a level of brain activity as measured by electroencephalography having a frequency of between four and seven cycles per second (associated with drowsiness in adults).

(phonology) The voiceless dental fricative represented by θ.