to rule out, to dismiss, to discard, to get rid of
Tom no podía descartar del todo la posibilidad de que Mary se hubiera suicidado.
Tom couldn't entirely rule out the possibility that Mary had committed suicide.
Tom no podía descartar la posibilidad de que no le gustara a Mary.
Tom couldn't rule out the possibility that Mary didn't like him.
Tom no pudo descartar la posibilidad de que él estuviera equivocado.
Tom couldn't rule out the possibility that he was wrong.