Actually I do mean the dictionary definition as well.
A throttle is the mechanism by which the flow of a fluid is managed by constriction or obstruction. An engine's power can be increased or decreased by the restriction of inlet gases (i.e., by the use of a throttle), but usually decreased. The term throttle has come to refer, informally and incorrectly, to any mechanism by which the power or speed of an engine is regulated.
Since both air and fuel are fluids and you regulate the fluid (diesel fuel) intake of a diesel compression ignition engine to regulate its speed, you are indeed "throttling" it.
Just pickin' nits.
