by Wolf Leslau is חם, which means "father-in-law" in Hebrew. Here is the entry, from page 25:
amat 'son-in-law, brother-in-law, daughter-in-law';
G. ḥam 'father-in-law';
Hebr. חם 'father-in-law'.
Note that while in Geez and Hebrew it only means father-law, it has completely different though related meanings in Amharic. I find this interesting because earlier, in a post on parashat bahaalotecha I suggested, and discovered that Ibn Ezra had suggested as well, that
while the pasuk described Yitro as the חותן משה, this might mean that he was the brother-in-law rather than the father-in-law, on the basis of other pesukim.
That we see a similar word function in a similar fashion in another language might lend credence to this suggestion.
Note also that the word means daughter-in-law in Amharic as well, presumable matching the Hebrew חמה. In a specific idea I've been developing about the threshing floor scene in Ruth (which I will not elaborate upon here, but some readers will know what I am talking about), I suggested that חמותה could mean daughter-in-law rather than mother-in-law, as it would normally mean (and we would expect כלתה anyway). But this might record an old usage of the term such that it is ambiguous and could mean daughter-in-law as well.