I am using the acronym package so as to automatically expand acronyms when they are first used. For example, I can simply type \ac{RMS}, and LaTeX automatically expands this to "Resource Management System (RMS)" or "RMS".

However, a problem occurs when using indefinite articles. The most common style, Abbreviation verbalised, requires the use of "a Resource" and "an RMS". Is there an easy way to deal with this in LaTeX?

Otherwise, have you seen articles where they use Word verbalised style?

2 Answers 2


This feature is available directly in the acronym package and I assume this was not the case when your question and David Carlisle's answer were posted. As you use \newacro (as opposed to \acro and \acrodef; see your linked PDF for the differences), David's example can be changed to



\newacro{RMS}[RMS]{Resource Management System}


zzzz \iac{RMS}  zzzz \iac{RMS}  

This gives you the same output as David's code and now you can simply use \iac and \Iac for lower and upper case indefinite articles. Note that - as far as I know - no special commands for forced formats like \acf, \acl, \acs come with the package.

Update: Note that using the acronym package with hyperref will make the indefinite article AND the acronym hyperrefs to the table of acronyms when using \iac. Further, also when using hyperref, there seems to be a bug when using \Iac multiple times on the same acronym that gives compiler errors. You can use this fix to get rid of these problems.

  • It might be a version thing, but \newacro and \newacroindefinite don't actually work for me, unless I drop the new part of both of them.
    – Ido_f
    Commented Jan 3, 2022 at 17:58
  • @Ido_f Are you creating a list? \newacro and variants should be used outside the acronym environment, while \acro and variants inside the acronym environment.
    – Dai Bowen
    Commented May 12, 2023 at 20:51

You can use the test that \ac uses to test for first use but make it make other texts, an and a here: (Please in future provide a working example, it would have made it much easier to answer).

enter image description here



\newacro{RMS}[RMS]{Resource Management System}

\expandafter\ifx\csname ac@#1\endcsname\AC@used%


zzzz \acrousedTF{RMS}{an}{a} \ac{RMS}  zzzz \acrousedTF{RMS}{an}{a}  \ac{RMS}  
  • I guess you could save yourself some keystrokes defining \def\acart#1{\acrousedTF{#1}{an}{a} \ac{#1}}
    – Seamus
    Commented Jul 17, 2012 at 22:17

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