Learn English – the “‑cide” word for killing one’s husband

Blackwell's Concise Dictionary of Social and Cultural Anthropology (2012) suggests mariticide (not to be confused with matricide):

Killing of one's own husband, or one who does this. Very rarely used. See also uxoricide.

There are many who object to this use. The original meaning of mariticide, it is said, was the killing of a spouse, regardless of the gender of the killer or the killed; maritus and marita are simply the masculine and feminine forms with the same Latin root, meaning spouse. Thus, it is argued, mariticide is no more a counterpart to uxoricide than marital is a counterpart to uxorial or parental to maternal.

Merriam-Webster, for instance, defines mariticide as

1. one that murders or kills his or her spouse
2. the act of a mariticide

There is no exclusive Latin word meaning husband, and thus no words to be derived from it to match uxorial, uxorious, and so on. But since mariticide is being used for this purpose, in a few years it is entirely possible that this use will be fully accepted. It has already made its way into Dictionary.com as

the killing of a spouse, esp. a husband by his wife

On the other hand, this use has already been around for a long time. From Punch, January 17, 1874:

The Yankees are said to have lately coined another new word to express the act, sometimes committed even in the United States, of a man who kills his wife. They call it "uxoricide." This is better than most of their additions to the Dictionary. They might have denominated wife-slaughter conjugicide; which would have been ambiguous. Uxoricide, having been established as a current expression, must of course be balanced with a name to signify the converse deed, which, by parity of nomenclature, will be termed mariticide.

The trend toward gender-neutrality argues for spousal homicide, which shows a sharp uptick in the last few decades, admittedly, like the others, from an extremely low base: _{Google Books Ngram}