1a or acai berry: a small, dark purple, berrylike fruit with a juicy pulp that is often used in beverages or eaten raw and that is produced by a tall, slender palm (Euterpe oleracea) native to tropical rain forests of Central and South America
b: the palm (Euterpe oleracea) that produces acai berries
2: a beverage made from the juice of the acai berry
Rio de Janeiro is the city that worships health and beauty and where the healthy and the beautiful drink acai.— Alex Bellosz
borrowed from Brazilian Portuguese assaí, uaçaí, açaí, the palm Euterpe oleracea, borrowed from Tupi *ɨβasaí, from ɨβá "plant, fruit" + an element of uncertain meaning