I am trying to change the linespacing within a marginnote such that it is different from the main document. I have tried all approaches described in Temporarily increase line spacing and Aligning margin note with line spacing different from main text, but none of them worked. Any ideas?
\documentclass{article}
\usepackage{setspace}
\usepackage{marginnote}
\begin{document}
\setstretch{1.25}
\renewcommand{\a}{One Two Three Four Five }
\newcommand{\newdef}[2][0]{\marginnote{{\setstretch{0.8}\emph{#2}}}[#1\baselineskip]}
\a\a\a\a\a\a\a\a\a\a\newdef{spanning multiple lines}
\a\a\a\a\a\a\a\a\a\a
\end{document}

Using
\newcommand{\newdef}[2][0]{\marginnote{{\setstretch{0.6}\emph{#2}\endgraf}}[#1\baselineskip]}
\a\a\a\a\a\a\a\a\a\a\newdef{spanning multiple lines; in this case even more than tree}
\a\a\a\a\a\a\a\a\a\a
I get



p. Why do you want to reduce baselineskip so much without reducing the font size? – David Carlisle Feb 19 '15 at 18:45