What are the names of the pieces of a question mark?

Solution 1:

If you're willing to go entirely by hearsay, a question mark has a curl, a lobe and a ball.

To quote:

Just as Kinky Friedman anthropomorphizes this B, giving it human characteristics, namely ribs, type designers have come up with some very human terms to describe the details of the letterforms that they create. They speak the arm (of, say, an E), the crotch (of an M), which could further be described as an acute crotch or an obtuse crotch, the ear (of some g’s), which might be a flat ear or a floppy ear, the eye (of an e), the leg (of a k), the shoulder (of an n), the tail (of a j or a Q), and the spine (of an S). There is a sketch by the great type designer Ed Benguiat that labels the curl, the lobe and the ball of a single question mark.

It's hearsay because I couldn't find a picture of Ed Benguiat's sketch, but if the linked blog is quoting reliably, then I would say this is a fair answer since Ed Benguiat is unquestionably an important expert in typeface design.

Solution 2:

I couldn't find any common typographical terminology for the top part so you could call the top bit:

• top part,
• squiggle,
• curl,
• curve,
• stroke.

You could call the bottom bit:

• bottom part,
• dot,
• jot,
• tittle,
• period,
• full stop.

A tittle is a small distinguishing mark, such as diacritic or the dot in the letter i and j, so I propose the terms squiggle and tittle.

Solution 3:

In The elements of typographic style by Robert Bringhurst, they are referred to as a hook / crook and a dot.