> Cleave is often cited as the go-to contronym: it can refer to splitting something apart and to uniting two things
Weird, I cannot remember ever seeing "cleave" used to mean "uniting two things".
"Inflammable" is my go-to example of a word that shouldn't exist in the English language. Causes too much confusion. I always use "flammable" and "nonflammable".
Here's an example I stole from the internet [1] "People in the remote mountain villages still cleave to their old traditions."
I'll leave other examples of cleavage meaning two things coming together to your imagination.
[1] https://dictionary.cambridge.org/dictionary/english/cleave-t...
With regards to "cleavage", I always thought that it was based on the other meaning of the word, the one about splitting things apart: https://www.merriam-webster.com/dictionary/cleavage
What about "inflammation" (from the same root), like what happens when you bruise yourself, or injure a joint? Is that OK?
Or you should you get a "flammation" instead?
Edit: Or when interpersonal tensions are high, and a situation becomes inflamed?
"Therefore shall a man leave his father and his mother, and shall cleave unto his wife: and they shall be one flesh." - Genesis 2:24