TITLE: How to say (pronounce) $\partial$ in the context of homology?
QUESTION [5 upvotes]: I am curious what is the common way to say (in English contexts) the name of $\partial$ (the boundary homomorphism) in homology theory. I.e. when giving a talk / speaking.
The boundary homomorphism is $\partial: C_n\to C_{n-1}$ when $(C_\bullet, \partial_\bullet)$ is a chain complex.
Some possibilities I can think of is: 

"Boundary"?
"Del"?
"Partial"?
"Dee"? (it looks like a letter $d$)
"Delta"?

Thanks for any insights. 
I haven't found any answer online despite some searching. How do you pronounce (partial) derivatives? is similar in a sense (same symbol $\partial$) but the context is entirely different.

REPLY [2 votes]: In my experience there is no single standard pronunciation, though "del" is probably the most common.  I have heard all of the possibilities you suggest except "delta" used.  If you want to maximize the chance that you will be understood, I would recommend just saying "(the) boundary of" rather than trying to pronounce it as a single word.  In cases where you really want a shorter pronunciation, I think "del" is probably the best choice, but as Mike Miller commented the most important thing is to be consistent and unambiguous.