(business, finance) A trading method whereby traders gather in person, often in a pit, and call out to all their desire to buy or sell a quantity at a given price, transactions being consummated when two parties can agree on a price. Most frequently used in securities markets.

A music, poetry, or comedy stage platform with open invitation, that is, where anyone is invited to perform.

(computing) A proxy server that may be accessed by any Internet user.

(finance) The total number of contracts outstanding between market participants in a market for futures, options, or other derivatives.

(Britain, Australia) a can opener.

A device used to open tin cans, usually by slicing the lid off. / (roller derby) A shoulder hit to the chest, usually accomplished while moving from a crouched to a standing position.

plural of eye-opener

(literally) Something that causes the eyes to open, or that opens the eyes. / (informal) Something that provides a sudden insight, or makes something clear that was previously mysterious.

(linguistics) A syllable that has no coda after its nucleus, and which hence ends in a vowel.

plural of open mic