Proto Polynesian: *Niu
REFLEXES IN SOME POLYNESIAN LANGUAGES:
Tongan, Samoan, Niue, Marquesan, Hawaiian, Tahitian, Tuamotu: Niu (Cocos nucifera, "Coconut palm & fruit", Arecaceae)
Takuu (Bouganville): Nui (Cocos nucifera, including fruit)
Manahiki (Cook Islands): Nī (Cocos nucifera), including fruit
Rarotongan: Nū (Cocos nucifera, including fruit)
Maori: Niu (A slender stick used in certain rituals; also a ceremonial pole [19th Century])

COGNATE REFLEXES IN SOME OTHER AUSTRONESIAN LANGUAGES
Ivatan (Philippines): Nioy (Cocos nucifera, "Coconut", including fruit)
Ilocano, Pangasinan (Philippines): Niog (Cocos nucifera, including fruit)
Tagalog (Philippines): Niyog (Cocos nucifera, including fruit)
Tausug (Southern Philippines): Niug (Cocos nucifera, including fruit)
Malay: Niur (Cocos nucifera, including fruit)
Kaiawa (Northern New Guinea): Niuk (Cocos nucifera, including fruit)
Sa'a (Solomon Islands): Niu (Cocos nucifera, including fruit)
Fijian: Niu (Cocos nucifera, including fruit)

RELATED WORDS WITH REFLEXES IN MĀORI
Nīkau, the palm Rhopalostylis sapida, from Proto Central Eastern Polynesian *Nīkau, "frond and nut of Cocos nucifera, and in some languages also the coconut palm itself".

These words with reflexes in Māori also at some point in their history referred to part of a coconut or coconut palm, as illustrated by their etymologies:

Kakano, "seed, flesh", from Proto Malayo Polynesian *kanen "something to be eaten, food"; through:

Proto Oceanic: *kanong, "flesh, inner substance; coconut flesh";
Proto Polynesian: *[ka]kano, "flesh, seed".
Cognate words in some other Polynesian languages:
Tongan: Kano, "flesh, substance"; kakano, "flesh, contents or substance";
Samoan: 'a'ano, "flesh; kernel, meat, including meat of coconut".
Hawaiian: 'ano, "kind, nature, moral quality, colour, meaning";
Marquesan: Kākano, "seed, grain"

Proto Polynesian: *fenu, "an element in weaving".
Cognate words in some other Polynesian languages:
Samoan: Fenū, "make a join in plaiting";
Tahitian: Fenu, "a single element in weaving a basket";
Tuamotuan: Henu, "to splice on; fibres of the aerial roots of the pandanus".

Proto Polynesian: *rama "fish at night with torches, torch", and
Proto Nuclear Polynesian: *lama, "tree used to make torches; torch"
Cognate words in some other Polynesian languages:
Tongan: Ama, "fishing with torches; torch made of coconut spathes"
Niuean: Ama, "search for crabs etc. with a torch"
Samoan: Lama, "torch made of dried coconut leaflets; to fish with torches; candlenut tree (Aleurites moluccana, Euphorbiaceae)"
Tahitian, Tuamotu: Rama, "torch, fishing with torches";
Hawaiian: Lama, "torch; the trees Diospyros hillebrandii and D. sandwicensis (Ebenaceae), symbols of enlightenment"

Through Proto Polynesian *kaka "cloth-like fibre surrounding base of coconut frond ".
Cognate words in some other Polynesian languages:
Tongan, Marquesan, Rarotongan: Kaka, "fibre at the base of a coconut frond"
Samoan: 'a'a, "fibre around base of coconut frond"
Tahitian: 'a'a, "brown fibrous membrane at the base of coconut fronds; similar substance at base of leaves of bamboo, sugar cane and reeds; skin to which fat about kidneys adheres; strainer for arrowroot"
Hawaiian: 'a'a'a, "coconut cloth; vasuclar bundles in taro corm; fibrous".

Proto Oceanic: *kapa "sennit (cord made from coconut fibre)"
Proto Polynesian: *kafa "sennit"
Cognate words in some other Polynesian languages:
Tongan: Kafa "sennit"
Samoan: 'afa "sennit"
Tahitian: Aha "sennit"
Hawaiian: 'aha "sennit"
Marquesan, Tuamotuan, Mangarevan: Kaha "sennit"
Rarotongan: Ka'a "sennit"

Proto Malayo Polynesian: *paqa "Stalk or stem of a plant" ~ *pa(q)paq, Probably "frond of a palm"
Proto Oceanic: *[pa]paq[a-] "frond of a palm" ~ baRabaRa "stem or stalk of non-woody plants like taro and banana, possibly also the soft portion of leaves"
Proto Polynesian: faqa "Stalk"
Cognate words in some other Polynesian languages:
Tongan: Fa'a "lower portion of leaf stalk"
Niue, Samoan, Marquesan, Tahitian+, Tuamotuan+: Fā "stalk" +of Taro, banana, & coconut
Rarotongan: 'ā "leaf stalk, especially of taro, plantain & coconut, including main spine of leaf"

Coconut palms are the symbol pa excellence of idyllic tropical islands and beaches. The nut has a water-resistant seal with plenty of air space in the layer of fibres underneath, so it floats easily and has the sea as a major agent of dispersal. The palm has also penetrated inland to about 300 metres above sea level (although it can be cultivated at higher elevations -- the photograph on the left was taken at the edge of a commercial plantation on an organic farm in Tupi, South Cotabato, Philippines, a little above the 300 metre mark).

The niu is very temperature-sensitive, growing naturally only within about 25 degrees of the equator (hence the strong association with tropical islands) and not thriving in places where the average annual temperature is less than about 22 degrees Centigrade, and there is a plentiful supply of moisture in the air and soil. It can stand lower temperatures, down to about 10 begrees C (50 degrees Fahrenheit) for short spells, and indeed I have seen young trees looking quite happy in a garden on Waiheke Island (38 degrees 46 sec. south, where on average the mean temperature reaches only about 21 degrees in February, the warmest month, and is less than 15 degrees in winter).

The tree is both graceful and resilient, growing to about 25 metres tall with a single, unbranched trunk and able to withstand severe buffeting from storms and tidal surges, although it does not stand up well to drought.

Commercially and practically, the coconut palm and its nut are a very valuable resource, with every part having been put to use by people. Coconut products, both as raw material and processed are major exports in the Philippines and other Southeast Asian countries, and in many Pacific Islands.

Coconut trunks make good bridges and road-beds over swampy ground. The timber is very durable can be used for building. The wood is is also excellent for making decorative containers and artefacts. The fronds are excellent for thatch, and the midribs also make handy brooms.

Sennit, cord made from coconut fibre, is especially valuable as it is both strong and resistant to sea water. It therefore can be used for lashing ocean-going canoes, as well as lashing adzes and house beams. Sails woven from sennit are used in blustery weather, replacing the less durable pandanus sails. The cord and fibre are also used in making elaborate ceremonial head dresses, like that illustrated in the section on "Further Information", below.

The flesh from the nuts is edible, or can be pressed for coconut milk and coconut cream, and yield an oil which can be used for cooking, as the base for cosmetics and soaps, or for making biodiesel. Coconut milk can also be infused with bacteria to produce electricity in biochemical fuel cells. Coconut water is a refreshing drink, and has no doubt saved the life of many a castaway. The flower spikes can be tapped for their sugar-rich sap, which can be boiled down to produce a low-glycemic sugar, or fermented for tubâ (coconut toddy), which in turn can be converted into vinegar.

The shells are used to make containers, cutlery and other domestic items, and are also good fuel. Coir, made from the fibre in the outer casing of the nut, is used in making a variety of items such as floor mats, brushes, stuffing for upholstery, and rope.

In the Philippines a genetic mutation gives rise to macapuno, a variety of coconut where the flesh is sweeter than normal and occupies much of the interior of the shell. It is an ingredient in many desserts and confections.