The
current FAR 23 words may be of use (you need to hyperlink to 23.335 as this link doesn't want to work as I had hoped) and, just above 23.335. is a downloadable picture of the envelope which might assist in understanding. If your penchant is for heavy metal, then the equivalent
current FAR 25 words will increase the level of mental distress once you hyperlink to 25.335 ....
The standard caveat applies .. the Standard is an evolving beast and the present words may be quite different to those which applied in the past to any particular aircraft model in question. To resolve this, it is necessary to look to the
Type Certificate Data Sheet for the particular machine and then find the archive version for the Design Standard.
I think Tinny's description is pretty close to the mark and generally adequate for pilot purposes ... and certainly a lot easier than wading through the rule swamp ...