In the following example I defined a \Defi command with two mandatory arguments; the first mandatory argument for the term to be defined and the second one, for the definition; the command typesets the term in boldfaced font, adds the term to the auxiliary file .def, and adds a \phantomsection command (this part requires the hyperref package) to get the proper anchor for the hyperlinks. The command \listofdefinitions will actually create the new "List of Definitions" using the kernel \@starttoc command. In the example the entries of the new list will be formatted as the figures in the LoF, but this can also be customized:
\documentclass{article}
\usepackage{hyperref}
\newcommand\Defi[2]{%
\noindent\makebox[1.5cm][l]{%
\textbf{#1}%
\phantomsection% comment out if hyperref is noy used
\addcontentsline{def}{figure}{#1}}{#2}\par}
\makeatletter
\newcommand\listdefinitionname{List of Definitions}
\newcommand\listofdefinitions{%
\section*{\listdefinitionname}\@starttoc{def}}
\makeatother
\begin{document}
\Defi{CDMA}{Code Division Multiple Access}
\Defi{GSM}{Global System for Mobile communication}
\Defi{NAD}{Nicotinamide Adenine Dinucleotide}
\Defi{TDMA}{Time Division Multiple Access}
\Defi{IC}{Integrated Circuit}
\Defi{BUT}{Block Under Test}
\listofdefinitions
\end{document}

Here's a version of the above code using the \newlistof command from the tocloft package:
\documentclass{article}
\usepackage{tocloft}
\usepackage{hyperref}
\newcommand\Defi[2]{%
\noindent\makebox[1.5cm][l]{%
\phantomsection% comment out if hyperref is noy used
\textbf{#1}%
\addcontentsline{def}{figure}{#1}}{#2}\par}
\newcommand\listdefinitionname{List of Definitions}
\newlistof{definition}{def}{\listdefinitionname}
\begin{document}
\Defi{CDMA}{Code Division Multiple Access}\newpage
\Defi{GSM}{Global System for Mobile communication}
\Defi{NAD}{Nicotinamide Adenine Dinucleotide}\newpage
\Defi{TDMA}{Time Division Multiple Access}
\Defi{IC}{Integrated Circuit}
\Defi{BUT}{Block Under Test}
\listofdefinition
\end{document}