Acronym
An acronym is an abbreviation consisting of initial letters that are read like an ordinary word.
Examples
English radar (pronounced [ˈreɪdɑɹ] ), from radio detection and ranging.
The English acronyms NATO, FOP and FEC are made out of North Atlantic Treaty Organization, First Order Principle and Free Element Condition, respectively. Some Dutch examples are: TROS, KNAV and DAF.
Comments
Acronyms contrast with alphabetisms, which are pronounced with the names of the letters (e.g. CD, HTML).
Polysemy
Sometimes acronym is used for abbreviations more generally, i.e. also for alphabetisms.
Origin
From Greek akro- 'tip' and -oonym- 'name'. The first attestation in the OED is from 1943.
Link
Utrecht Lexicon of Linguistics