I use a lot this small column definitions for this kind of things --- I hope they can help (and give hints on how to modify them to your tastes):
\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{array, ragged2e}
\newcolumntype{P}[1]{>{}p{#1\linewidth}<{}}
\newcolumntype{R}[1]{>{\RaggedRight\arraybackslash}p{#1\linewidth}<{}}
\newcolumntype{M}[1]{>{\RaggedRight\arraybackslash}m{#1\linewidth}<{}}
\newcommand{\longtext}{This is quite a long test, but not so long
as the text you get with \texttt{lipsum}, just to check things out.}
\begin{document}
\begin{tabular}{|c|c|P{0.3}|}
\hline
kind: & \texttt{P}-column & \longtext \\
\hline
\end{tabular}
\begin{tabular}{|c|c|R{0.3}|}
\hline
kind: & \texttt{R}-column & \longtext \\
\hline
\end{tabular}
\begin{tabular}{|c|c|M{0.3}|}
\hline
kind: & \texttt{M}-column & \longtext \\
\hline
\end{tabular}

Normally justified text come out badly in small columns; I normally prefer using \raggedright or, better, \RaggedRight for this kind of text.
The \arraybackslash it's here to avoid the infamous Misplaced noalign error...
p{<width>}type column (as opposed toc) that formats as paragraph text. – Steven B. Segletes May 11 '16 at 04:33