OTR

Otr or OTR may refer to:
 * Ótr, a dwarf in Norse mythology
 * Otr, the abbreviation for the orchid genus Otaara
 * Coto 47 Airport, an airport that serves Coto 47, Costa Rica

OTR may refer to:
 * Optical Transition Radiation, in physics, the radiation emitted by a charged beam at the interface between two mediums
 * Oxygen transmission rate, a measure of a barrier material's oxygen permeability
 * Organisation and Technology Research (OTR plc), a European information technology research company
 * Over-the-Rhine, the Cincinnati, USA neighborhood
 * On the Run (convenience store), an international convenience store chain owned by ExxonMobil
 * Occupational Therapist Registered
 * On The Road. Generally refers to the total price of a vehicle including all costs required to legally drive the vehicle, but possibly excluding insurance. This will therefore include the purchase price plus any applicable taxes.
 * Off-the-road tires, for construction or mining vehicles
 * One Touch Recording, a way to instantly record television programmes onto video cassette

In media:
 * Old-time radio, or "Golden Age Radio", a term describing an era of radio programmes in the first half of the 20th century
 * Off The Record (OTR/PRESS News Agency), a Spanish newswire for media
 * Off The Record (TSN TV series), a Canadian sports talk show

In computers
 * Off-the-Record Messaging, an instant messaging encryption system

In finance
 * On the run (finance), used to describe the most recently issued security

In music:
 * On The Rocks (band), a rock band featuring British, Dutch and Brazilian members
 * Over the Rhine (band), an Ohio, USA based band
 * Otierre or OTR (Originale Trasmissione del Ritmo), an Italian hip hop band

In Slang:
 * Off the Ricter, Out of control, Off hand, Highest form of
 * Off the Ricta, Surfer in total control, Highest form of skill
 * On the REG, doing something regularly. Generally, "On the Reg" refers to frequently doing something that is remarkable or incredibly fun. Generally used in reference to partying vigorously.
 * On the rag, slang for a woman's period, menstrual cycle

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