How come shameful and shameless mean the same thing?

Dear Cecil: It seems to me that “shameful” and “shameless” basically mean the same thing, yet one is “full” and the other is “less.” How is this possible? Katherine C., Van Nuys, California

Cecil replies:

Shameful and shameless don’t mean the same thing. A shameful act is one that ought to inspire a sense of shame in its author. If said person is shameless (brazen), however, it doesn’t. As one of my affronted relatives once told me, many of the questions we address in this column are shameful. Luckily, we’re shameless.

Cecil Adams

Send questions to Cecil via cecil@straightdope.com.