A Butter

1. A soft, fatty foodstuff made by churning the cream of milk (generally cow's milk).
2. Any of various foodstuffs made from other foods or oils, similar in consistency to, eaten like or intended as a substitute for butter (preceded by the name of the food used to make it).
3. (obsolete, chemistry) Any specific soft substance.
4. (aviation, slang) A smooth plane landing.