# How to have a word floating to the left of a paragraph

I am trying to achieve the same as what is shown in the figure below. Basically, I would like to have a word, or a couple of words, floating to the left of a paragraph where the term is first introduced.

This significantly improves readability and the identification of all the terms used in a background section, but I have no clue of how can I do this.

What LaTeX packages could I use to achieve this effect?

This is often referred to as a \marginpar.

\documentclass{article}

\usepackage{newpxtext}

\begin{document}

In most collections, the same concept may be referred to using different
words. This issue, known as \marginpar{\textsc{synonymy}}\emph{synonymy}, has an impact on the recall of most
information retrieval systems. For example, you would want a search for
\textsf{aircraft} to match \textsf{plane} (but only for references to an \emph{airplane}, not a woodworking
plane), and for a search on \textsf{thermodynamics} to match references to \textsf{heat} in
appropriate discussions.

\end{document}

Positioning on the left or right is possible via \marginpar[<left>]{<right>} when in twoside mode. You could also consider using the marginnote package, depending on the depth of usage.