How to Make “Properties” Bold in a LaTeX List

The text in \begin{properties} is the name of a LaTeX environment. LaTeX uses it to start an environment, but does not print the name on the page. To display a bold heading, write \textbf{Properties} in the document where you want that heading.

If you mean the word “Property” or the number at the start of each list item, format the list label instead. The enumitem package provides a label option for this.

Bold a heading

Place the bold text before the environment:

\textbf{Properties}
\begin{enumerate}
  \item First property.
  \item Second property.
\end{enumerate}

This makes only the heading bold. The list items remain in the normal font.

Bold the labels in an enumerate list

Load enumitem and set the label format. This complete example defines a properties environment whose item labels are bold:

\documentclass{article}
\usepackage{enumitem}

\newenvironment{properties}
  {\begin{enumerate}[label=\textbf{Property \arabic*:}]}
  {\end{enumerate}}

\begin{document}

\textbf{Properties}
\begin{properties}
  \item Every square is a rectangle.
  \item The diagonals of a rectangle are equal in length.
\end{properties}

\end{document}

The heading is printed because of \textbf{Properties}. The environment definition controls the list: label=... sets what appears before each item, and \arabic* inserts the current item number. Because the whole label is inside \textbf{...}, both “Property” and its number are bold. The colon is included in the label as well.

If you already have a properties environment, you usually do not need to define it again. Find its definition and adjust the enumerate options there. For example, if it currently contains \begin{enumerate}, change that to \begin{enumerate}[label=\textbf{Property \arabic*:}], assuming enumitem is loaded.

Bold only part of the label

You can put only the text you want bold inside \textbf. For example:

\begin{enumerate}[label=\textbf{Property} \arabic*:]

Here, “Property” is bold, while the number and punctuation are not. To bold just the number, use label=Property \textbf{\arabic*}:.

Common mistakes

• Expecting the environment name to print: \begin{properties} is an instruction, not a heading. Add visible text such as \textbf{Properties} yourself.
• Using \textbf around the environment command: \textbf{\begin{properties}...} is not the right way to style a list label and can cause grouping or environment errors. Apply formatting to the heading or label instead.
• Forgetting the package: The optional label setting shown above requires \usepackage{enumitem}.
• Changing item text when you only mean to change labels: The label option changes the marker before each \item; it does not bold the item’s sentence.