Marc Branchaud [off-list ref] writes:
(BTW, on this list we pronounce "the name of the commit" as "the
commit subject (line)".)
Yup. "subject" probably comes from the fact that the title (the
first paragraph, folded into a single line) of the commit is used on
the "Subject:" header when formatted for e-mail submission, and also
's' in "git log --pretty='%s'" is described as "subject" in the
documentation. Other words I've seen used are "commit title" and
"oneline description", but "subject" would be the most common, I
suspect.
"commit name" on the other hand brings a different concept, i.e.,
"the commit object name", more strongly to readers' minds, and can
be mistaken as what you'd get in "git log --pretty='%H'".