Reading a review of the 1983 fantasy film Hundra (a feminist knockoff of Conan the Barbarian), I came across a pretty unusual word, albeit one that almost looks perfectly normal. Film historian Paul Mavis, at DVD Talk, says the film’s creators:
set about to make a spoofy fantasy adventure thats focus would be on a gorgeous, blonde, man-hating super-warrior who was subservient to no one.
Few readers would pause over that thats: its meaning is clear in context, and it draws little attention to itself, its ungrammaticality thoroughly overshadowed by the line’s sensational imagery. Who’d be distracted by the subtle asymmetry of English’s relative pronoun system when there are man-hating super-warriors striding about?
Editors, that’s who. And this is one reason I like reading texts that (presumably) aren’t professionally edited: you never know what kind of morphological oddity will appear. And it is a curio: scouring vast language corpora for thats produces only false negatives – apostrophe-less that’s.
Centuries ago, English had various word endings for relative pronouns’ different grammatical cases. For instance, that was þæt, which in the possessive (aka genitive) was þæs. Jonathon Owen has a good rundown of this at Arrant Pedantry. Over time, English lost these inflections and was left with a diminished set – which is why whose and of which now do the work of þæs.
You can see why even a native speaker and competent writer, for whom whose didn’t come readily to mind (or who felt, erroneously, that it was wrong for a non-human antecedent) might instinctively fill the gap in “an adventure ___ focus would be…” with thats. In a parallel world, it could have developed as a normal part of the relative pronoun system.
But it didn’t, and unless I see thats a few more times, I won’t expect a resurgence. That and which simply don’t have genitive forms like *thats or *which(e)s available in modern standard usage. The option of whose or of which is an imperfect state of affairs, but there it is. Hundra‘s tagline, “She will not be tamed”, goes double for English.
Arnold Zwicky, by email, has brought to my attention an article by Neal Whitman at the Visual Thesaurus which looks at possessive that’s among other things; and a brief post by John Lawler at Linguist List in 1993, which subsequently featured in at least two books on syntax.