ost

plural osts

1. obsoleteObsolete form of oast.

plural OSTs

1. abbreviationinitialismInitialism of original soundtrack.

   I really like the OST of that game.

1. abbreviationinitialismspacelawInitialism of Outer Space Treaty: a treaty that represents the basic legal framework of international space law, signed in 1967.

   1 more example

   The most important source of space law is the 1967 Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies (OST).¹⁶ […] The OST is a product of the Cold War era when the United States and the Soviet Union—the only states with spacefaring capability—were bitter rivals, each fundamentally distrustful of the other.

   2014, John G Sprankling, “Rights in Airspace and Outer Space”, in The International Law of Property, Oxford University Press, →ISBN, page 176

2. abbreviationinitialismInitialism of Open Skies Treaty.
3. UKabbreviationhistoricalinitialismgovernmentInitialism of Office of Science and Technology.