A person who stinks.
A contemptible person.
I won't date Mary Jane again. I thought she was a stinker to leave before the end of the movie.
Something difficult (e.g. a given puzzle) or unpleasant (e.g. negative review, nasty letter).
Today's crossword is a stinker.
Something of poor quality.
Any of several species of large Antarctic petrels which feed on blubber and carrion and have an offensive odour, such as the giant fulmar.
A chemist.
A hot day.