would generally qualify as word acronyms among those who use that term. There is also some disagreement as to what to call an abbreviation that some speakers pronounce as letters but others pronounce as a word. For example, the terms URL and IRA (for individual retirement account) can be pronounced as individual letters: and , respectively; or as a single word: and , respectively. The same character string may be pronounced differently when the meaning is different; IRA is always sounded out as I-R-A when standing for Irish Republican Army. The spelled-out form of an acronym, initialism, or syllabic abbreviation (that is, what that abbreviation stands for) is called its expansion. Lexicography and style guides It is an unsettled question in English lexicography and style guides whether it is legitimate to use the word acronym to describe forms that use initials but are not pronounced as a word. While there is plenty of evidence that acronym is used widely in this way, some sources do not acknowledge this usage, reserving the term acronym only for forms pronounced as a word, and using initialism or abbreviation for those that are not. Some sources acknowledge the usage, but vary in whether they criticize or forbid it, allow it without comment, or explicitly advocate for it. Some mainstream English dictionaries from across the English-speaking world affirm a sense of acronym which does not require being pronounced as a word. American English dictionaries such as Merriam-Webster, Dictionary.com's Random House Webster's Unabridged Dictionary and the American Heritage Dictionary as well as the British Oxford English Dictionary and the Australian Macquarie Dictionary all include a sense in their entries for acronym equating it with initialism, although The American Heritage Dictionary criticizes it with the label "usage problem". However, many English language dictionaries, such as the Collins COBUILD Advanced Dictionary, Cambridge Advanced Learner's Dictionary, Macmillan Dictionary, Longman Dictionary of Contemporary English, New Oxford American Dictionary, Webster's New World Dictionary, and Lexico from Oxford University Press do not acknowledge such a sense. Most of the dictionary entries and style guide recommendations regarding the term acronym through the twentieth century did not explicitly acknowledge or support the expansive sense. The Merriam–Webster's Dictionary of English Usage from 1994 is one of the earliest publications to advocate for the expansive sense, and all the major dictionary editions that include a sense of acronym equating it with initialism were first published in