\documentclass{article}

\usepackage{glossaries}
\makeglossaries

\newglossaryentry{Physics}{
  name=Physics,
  description={is the study of stuff}
}

\begin{document}

To solve various problems in \Gls{Physics} it can useful to express any arbitrary piecewise-smooth function as a Fourier Series composed of multiple sine and cosine funcions.

\printglossaries

\end{document}