In the wake of Julia Gillard’s now-viral speech, Macquarie Dictionary has moved to amend its definition of misogyny. The backlash has been quick.

Barnaby Joyce has called Macquarie’s decision “convenient”; NSW Nationals Senator Fiona Nash thinks this could set a precedent whereby the dictionary becomes a defence against criticism of the PM. S-xism, for instance, could be redefined as “any criticism of the Prime Minister”, and budget surplus “a mythical accounting trick popular with voters”.

Both appear to misunderstand Macquarie’s motivations, and the purpose of a dictionary. But more on that later. First, let’s look at what Gillard meant by misogyny. Here’s one example from her speech:

“I was offended too by the s-xism, by the misogyny of the Leader of the Opposition catcalling across this table at me as I sit here as Prime Minister, ‘If the Prime Minister wants to, politically speaking, make an honest woman of herself…’, something that would never have been said to any man sitting in this chair.”

What Gillard seemed to be implying about Abbott was not that he hates women, but that he shows prejudice against women, or perhaps women in power, and she provided ample documentary evidence to suggest that this is indeed the case. This would seem to align more with a typical definition of s-xism than Macquarie’s current definition of misogyny/.

Macquarie’s new definition, “an entrenched prejudice against women”, matches Gillard’s use, the use of the word in media reports and by much of the general public. The current definition, one assumes, will still be retained in clinical psychology.

Was Gillard wrong to use the word this way? Not necessarily, no. While it impedes good communication to use a word with a different meaning to everyone else, this is not what she was doing. She used the word in a way that most people understand, even though it is not exactly the dictionary definition. Some other dictionaries, for example (popular, but not necessarily completely reliable), already have a more general definition: “hatred, dislike, or mistrust of women” and the Oxford English Dictionary (up there in the reliability stakes) defines misogyny as “hatred or dislike of, or prejudice against women”.

Once a majority of the population understand a particular meaning of a word, a dictionary changes to reflect current use. This change is not caused by Gillard’s speech; her use corresponds to the meaning that is already in most people’s own vocabularies.

It is important to point out one of the primary purposes of a dictionary: to record the past and present usages of words and their definitions. If the general use changes, the dictionary changes to match it, hopefully with as little lag as possible. In the good old days when dictionaries took entire bookshelves, you might be waiting decades for a dictionary to catch up to contemporary usage; by the time it’s published, it’s already out of date. In this brave new digital world though, changes to dictionaries can happen much quicker — Macquarie expects its updated definition of misogyny to be published online this year, and in print late next year.