The Collaborative International Dictionary of English v.0.48:
menu \men"u\ (m[e^]n"y[=oo]), n. [F., slender, thin, minute. See
1. The details of a banquet; a list of the dishes served at a
meal, whether or not one has a choice.
2. Any list of objects, activities, etc. from which to
choose; a selection of alternatives.
3. Hence:A list of dishes form which to choose at a
restaurant; a bill of fare.
4. Hence: (Computers) A list displayed on the computer
screen, by which a program provides the user with
different options for processing by the program. It
usually includes a mechanism, such as pointing by a mouse
or selection by arrow keys, to select the desired option
from those on the list. Depending on how the menu is
displayed, it may be a pop-up menu or pull-down menu.
The Free On-line Dictionary of Computing (18 March 2015):
(Or "drop-down menu", "pop-down menu") A
menu in a graphical user interface, whose title is
normally visible but whose contents are revealed only when the
user activates it, normally by pressing the mouse button
while the pointer is over the title, whereupon the menu
items appear below the title. The user may then select an
item from the menu or click elsewhere, in either case the menu
contents are hidden again. A menu item is selected either by
dragging the mouse from the menu title to the item and
releasing or by clicking the title and then the item.
When a pull-down menu appears in the main area of a window, as
opposed to the menu bar, it may have a small,
downward-pointing triangle to the right.
Compare: scrollable list.