means A hardy leafy green cabbage relative with tough, curly or flat dark leaves, eaten cooked or raw and beloved by the health-conscious.

from From the Old English 'cawel' or 'cal,' itself borrowed from Latin 'caulis' meaning 'stem' or 'cabbage stalk' — the same root that gives us 'cauliflower' and 'coleslaw' (literally 'cabbage salad'). The form 'kale' is particularly Scots and northern English, where it long meant cabbage of any kind; in Scotland 'kail' could even stand in for dinner itself, since a pot of it was so often what was on the table.