I'm trying to format a description list with small caps for the labels and have the body text a standard distance from the left margin. When I use capitals in the labels (in the real list they are abbreviations and acronyms) and try to force lowercase and then small caps, I only get the first letter in small caps. Also, the "leftmargin" option seems only to apply if there is a second line (i.e., like a hanging indent). I'd like all the body text to be indented the same amount from the left margin, regardless of the size of the label.
\documentclass[11pt]{memoir}
\usepackage{enumitem}
\begin{document}
\begin{description}[leftmargin=4cm,font=\normalfont\scshape\MakeLowercase]
\item[FIRST] My definition here
\item[NEXT] and another one
\item[AFTER] This is the third
\end{description}
\end{document}
\MakeLowerCase
works like\textsc{}
not like\scshape
i.e. it needs an argument, so can't be used like a font declaration.