List of Acronyms and Initialisms: O

List Of Acronyms And Initialisms: O

This list contains acronyms, initialisms, and pseudo-blends that begin with the letter O.

For the purposes of this list:

• acronym = an abbreviation pronounced as a series of constituent letters, e.g., SARS = severe acute respiratory syndrome
• initialism = an abbreviation pronounced wholly or partly using the names of its constituent letters, e.g., CD = compact disc
• pseudo-blend = an abbreviation whose extra or omitted letters means that it cannot stand as a true acronym, initialism, or portmanteau (a word formed by combining two or more words).

(a) = acronym in the example: SARS – (a) Severe acute respiratory syndrome

(i) = initialism in the example: CD – (i) Compact disc

(p) = pseudo-blend in the example: UNIFEM – (p) United Nations Development Fund for Women

(s) = symbol (none of the above, representing and pronounced as something else; for example: MHz – Megahertz)

(Main list of acronyms and initialisms)