[Tex/LaTex] tcolorbox: designing a definition with \tcbmaketheorem

Question

I want to make a tcolorbox that says Definition: in the title and that is it.

\documentclass{article}
\usepackage[most]{tcolorbox}
\tcbuselibrary{theorems}
%  defi enviro                                                                      
\tcbset{
  theorem/.style args = {#1}{%                                                      
    title = {\mbox{#1} :},
  }
}
\tcbmaketheorem{Definition}{Definition}{%                                         
  colframe = gray!black!50,
  fonttitle = \bfseries
}
\begin{document}
\begin{Definition}{Definition}
  Some definition.
\end{Definition}
\end{document}

Answer 1

Since you don't want numbering, nor anything special, you can simply use \newtcolorbox:

\documentclass{article}
\usepackage{tcolorbox}
\usepackage{lipsum}

\newtcolorbox{mydef}{title=Definition:}

\begin{document}

\begin{mydef}
\lipsum[4]
\end{mydef}

\end{document}