My roommate asked me how to spell the first word of Till death do us part (for reasons that I don’t fully recall, but it definitely wasn’t because we were starting some odd sort of relationship). We agreed there were three possibilities:

til, till, ’til

I quickly responded that ’til was the logical choice, a truncation of until, with the missing un marked by an apostrophe. Open-and-shut case. Except that it wasn’t. It kept gnawing at me. Had I seen people use till in that context? Why would they do that? So I made the same mistake I often do, and I looked into exactly what the deal was. First off, let’s look at some proponents of each form:

‘Tils:

‘Til Tuesday, Aimee Mann’s semi-pivotal 80s band

‘Til Death, Brad Garrett’s follow-up to Everybody Loves Raymond

Waiting ‘Til the Midnight Hour: A Narrative History of Black Power in America

Tills:

Till Death Us Do Part, British sitcom that paved the way for All in the Family

From Dusk Till Dawn, movie featuring Salma Hayek dancing and (so it is rumored) some other plot as well.

(Til is hard to find attestations of — people seem to be pretty good at remembering to put apostrophes at the words when the first syllable is removed.) So why would anyone spell it till if it’s coming from until? Well, it turns out that till isn’t derived from until. Till and ’til are actually two different words with two different etymologies. Till is the earlier form, attested as early as 1330; Until is actually derived from till, not the other way around as in ’til (a backformation which showed up much later). Both are common, so it’s up to you which one you like. Till is commoner in Scotland, where it can be used like dative to in some situations, while ’til is commoner in the U.S. Take your pick.