You can define a new command that way:
\newcommand\mynote[1]{\footnotesize#1}
A better solution, in my opinion, would be to load the threeparttable
package and write in the preamble:
\usepackage{etoolbox}
\AtBeginEnvironment{tablenotes}{\footnotesize}
Then use the environment as follows:
\begin{table}
\begin{threeparttable}
\begin{tabular}{xxx}
............
\end{tabular}
\begin{tablenotes}
\item[] Note/explanation1
\item[] Note/explanation2
..........................
\end{tablenotes}
\end{tabular}
\end{threeparttable}
\end{table}
The notes will have the width of the table. For figures, the corresponding environment is measuredfigure
.
For long tables, you'll use the threeparttablex
package. The syntax is slightly different: the environment is now ThreePartTable
and the TableNotes
environment is written at the beginning of the environment; the notes are inserted anywhere you want with the \inserTableNotes
command, and they can be referenced. Finally, you have a \setTableNoteFont
command.