Last week we talked about "late," a short word with a laundry list of definitions. As such, "late" also has a fair number of superalative and comparative forms, which brings us to this week.
"Late" has two comparative forms in English: later and latter, with "later" being the more typical form. "Latter" is the older of the two and is used primarily to refer to the last member of a named group of two, in opposition to "former."
For example, in relation to recent news we could say, "The threat of sanctions and the effect of sanctions are two different things. The latter will significantly weaken Russia." Here, "latter" refers to the effect of sanctions, while the threat of sanctions would be considered the former.
Some usage guides say "latter" and "former" should only be used when there are two things that are being referenced. However, actual print usage shows that "latter" is used reasonably regularly to refer to the last item in a list of more than two things. So, if that's a thing you do, there's no need to worry.
"Latter' is also used to refer to times near the end of something in a way that is very similar to "later." For example, "In his latter years, after he retired, he took up pottery."
When it comes to superlative forms of "late," there are three options: latest, last, and latemost.
Let's get "latemost" out of the way first, because it probably looks a bit weird to many of you. It's an archaic term that has become very specialized and isn't likely to appear in many standard dictionaries. However, it is sometimes used in geology, e.g. "It extended from latemost Triassic to Middle Jurassic times."
In more familiar terms, "latest" usually means most recent, whereas "last" tends to mean final, both in time and space. For example, "the last time showing of the movie tonight" or "the last house on the right."
"Last" can also mean "most recent," as in, "In the last episode we found out more about the main character's past." Here, most of us would probably assume that "last episode" refers to the episode that aired previously, not the final episode. However, some usage guides would argue that "latest episode" should be used instead to avoid any ambiguity.