Can Multiply be used as noun, such as in "matrix multiply"? I heard of this from some Americans.
Or should it be "matrix multiplication" instead?
It needs to be "multiplication". "Multiply" is strictly a verb.
Agree with FumbleFingers. The experts from any domain have their own language and way of convincing the message. I'm a healthcare provider and while describing/discussing medical things among us, we generally overlook grammar because for us, that's trivial in that case.
I searched several dictionaries but could not find the word multiply as a noun. In my pro version of WordWeb (cannot give link here as it's not online) it says...
Multiply as a verb and adjective. Derived: Noun: multiple, multiplication, multiplier.
I further tried to understand the term in mathematics as well. As you got it right, the correct term is Matrix Multiplication. So, maybe, the experts use it in an informal way but the message is convinced.
Multiply can be a noun. As in, "I performed one multiply followed by two adds." In this case, a multiply refers to a mathematical operation. It's often used this way in math and computer science.
It's similar to how we say, "I went for a run." run is normally a verb but in this case it's a noun.