\theoremstyle{plain}
\newtheorem{thm}{Teorema}[chapter]
\newtheorem{theorem}[thm]{Teorema}
\newtheorem{teorema}[thm]{Teorema}
\newtheorem{theoreml}[thm]{Theorem}

\newtheorem{lemma}[thm]{Lema}
\newtheorem{corollary}[thm]{Corolario}
\newtheorem{corolario}[thm]{Corolario}
\newtheorem{proposition}[thm]{Proposici{\'o}n}
\newtheorem{proposicion}[thm]{Proposici{\'o}n}
\newtheorem*{teoremasn}{Teorema}

\theoremstyle{definition}
\newtheorem{defn}{Definici{\'o}n}[chapter]
\newtheorem{definicion}[defn]{Definici{\'o}n}
\newtheorem{definition}[defn]{Definici{\'o}n}
\newtheorem{conjetura}[defn]{Conjetura}
\newtheorem{ejemplo}[defn]{Ejemplo}

\theoremstyle{remark} 
\newtheorem*{remark}{Remark}
\newtheorem*{note}{Nota} 
\newtheorem*{case}{Caso}
\newtheorem*{nota}{Nota} 
\newtheorem*{caso}{Caso}