Q. My significant other and I have a disagreement: he maintains that in referring to a roomful of nurses, we may say “a roomful of R.N.” on the grounds that we do not need to pluralize R.N. as R.N.s, although he does concede that one would not say “a roomful of nurse.” (“Room full” perhaps irrationally connotes to me a more ominous density of nurses than “roomful.”) We have been arguing about this for going-on ten years and would like to settle the question in order to move on to some new dispute.

A. To my ear, a roomful of R.N. sounds far more ominous than a roomful of RNs. But as you can see, Chicago style regularly pluralizes abbreviations and skips the pesky periods: “a roomful [or room full] of RNs.” Maybe you can argue about the periods from now on.