The same as palm. I learned the word ладонь listening to this song: https://www.youtube.com/watch?v=Ra0ozaE-oy0
I very strongly recommend everybody to listen to Russian songs, great learning tool :D
Also, wiktionary is very reliable https://en.wiktionary.org/wiki/%D0%BB%D0%B0%D0%B4%D0%BE%D0%BD%D1%8C
It might not be always absolutely detailed, but its declension tables are priceless.