Choy sum or choi sum literally means "vegetable

Vegetable

The noun vegetable usually means an edible plant or part of a plant other than a sweet fruit or seed. This typically means the leaf, stem, or root of a plant....

 heart

Heart

The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...

" in Cantonese

Cantonese

Cantonese is a dialect spoken primarily in south China.Cantonese may also refer to:* Yue Chinese, the Chinese language that includes Cantonese* Cantonese cuisine, the cuisine of Guangdong province...

. While frequently used to describe edible stem of either of the two varieties of Chinese cabbage

Chinese cabbage

Chinese cabbage can refer to two distinct varieties of Chinese leaf vegetables used often in Chinese cuisine. These vegetables are both related to the Western cabbage, and are of the same species as the common turnip...

, usually the soft inner core of bok choy with the tougher outer leaves

Leaf

A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....

 removed, the term can be applied to the "heart"–the soft core or flower

Flower

A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...

ing stem–of almost any vegetable such as kai-lan

Kai-lan

Kai-lan, also known as Chinese broccoli, is a leaf vegetable featuring thick, flat, glossy blue-green leaves with thick stems and a small number of tiny, almost vestigial flower heads similar to those of broccoli. Broccoli and kai-lan belong to the same species Brassica oleracea, but kai-lan is in...

, including non-traditionally East Asian greens such as broccoli

Broccoli

Broccoli is a plant in the cabbage family, whose large flower head is used as a vegetable.-General:The word broccoli, from the Italian plural of , refers to "the flowering top of a cabbage"....

. Outside of China

China

Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

, the Cantonese spelling of choy sum is more common than the standard Mandarin pinyin

Pinyin

Pinyin is the official system to transcribe Chinese characters into the Roman alphabet in China, Malaysia, Singapore and Taiwan. It is also often used to teach Mandarin Chinese and spell Chinese names in foreign publications and used as an input method to enter Chinese characters into...

 spelling càixīn due to the greater influence of Cantonese cuisine

Cantonese cuisine

Cantonese cuisine comes from Guangdong Province in southern China and is one of 8 superdivisions of Chinese cuisine. Its prominence outside China is due to the great numbers of early emigrants from Guangdong. Cantonese chefs are highly sought after throughout the country...

 in the West

Western world

The Western world, also known as the West and the Occident , is a term referring to the countries of Western Europe , the countries of the Americas, as well all countries of Northern and Central Europe, Australia and New Zealand...

.