mash potato
/ˌmaʃ pəˈteɪtəʊ/Now chiefly US
noun
1= mashed potato.
2Also with capital initials. = mashed potato.
Origin
Late 18th century; earliest use found in James Woodforde (1740–1803), diarist and Church of England clergyman. Probably partly from mash + potato, and partly shortened from mashed potato.