It is related to the concept of tapu or tabu found in other Polynesian cultures, from whence came the English word "taboo."
The Hawaiian word kapu is usually translated to English as "forbidden", though it also carries the meanings of "keep out", "no trespassing", "sacred", "consecrated", or "holy".
The Kahili were restrictions placed upon contact with chiefs (kings), but these also apply to all people of known spiritual power.
It was kapu when entering a chief's personal area to come in contact with his hair or fingernail clippings, to look directly at him, and to be in sight of him with a head higher than his.
Wearing red and yellow feathers (a sign of royalty) was kapu, unless an individual was of the highest rank.
[3] The kapu system was used in Hawaii until 1819, when King Kamehameha II, acting with his mother Queen Keōpūolani, his father's other queen Kaʻahumanu, and Kahuna-nui Hewahewa, abolished it by the symbolic act of sharing a meal of forbidden foods with the women of his court.