How did the terms "abscissa", "ordinate", and "applicate" (for the $x$-axis, $y$-axis, and $z$-axis, respectively) originate?
Note: I feel the need to explain this question before someone says that this is opinionated or unnecessary. I think that it's very, very useful to know how certain terms originate in mathematics because it allows us to understand everything deeper. It's always great to know our math ancestors named certain things in certain ways because we can then sort of "see" how these terms and concepts came about.
From the "Earliest Known Uses of Some of the Words of Mathematics" pages ...
and
"Earliest Known Uses..." doesn't have an entry for "applicate". The Math Forum has a Dr. Math thread about the term, referencing PlanetMath as a source. I can't seem to find the PM entry, but here's part of it as quoted in the thread:
There's no mention of how that particular term originated, however. (As with Dr. Math respondent, I'd never heard the term.)