It is not often that one finds a word new to the Oxford English Dictionary. The word in question is OHEEROO, which is first found in a very rare pamphlet entitled Obervations on the Oheeroo, a palm-tree, published in London in 1784. Only two copies of this are known: both in the British Library. In the copy shelfmarked T.157(9) there is a manuscript letter signed "Uden" - probably Conrad Friedrich Uden, who may have been the author of the tract. It is said that the name is derived from Arawak Indian: this I have not been able to verify as yet, though "Roo" is still used in Trinidad creole for "tree".
On the subject of words new to OED I shall be shortly posting here some botanical words derived from early nurserymens' seed and plant catalogues which figure in Volume XVII of my Bibliography of the English Language, devoted entirely to the language of botany and horticulture 1525-1800. These early catalogues are a rich but neglected source for plant vocabulary. The earliest catalogues date from the 1670s.