Use \emph when giving local meaning to a word

chapters/functions.tex

@@ -1603,10 +1603,8 @@ \section{Declaring Inverses of Functions}\label{declaring-inverses-of-functions}
 \end{example}
 \section{External Function Interface}\label{external-function-interface}
 
-Here, the word function is used to refer to an arbitrary external
-routine, whether or not the routine has a return value or returns its
-result via output parameters (or both). The Modelica external function
-call interface provides the following:
+Here, the word \emph{function} is used to refer to an arbitrary external routine, whether or not the routine has a return value or returns its result via output parameters (or both).
+The Modelica external function call interface provides the following:
 \begin{itemize}
 \item
   Support for external functions written in C (specifically C89) and