cranberry (n.)

name of the fruit of several species of a swamp-growing shrub, 1640s, apparently an American English adaptation of Low German kraanbere, from kraan "crane" (see crane (n.)) + Middle Low German bere "berry" (see berry). The reason for the name is not known; perhaps they were so called from fancied resemblance between the plants' stamens and the beaks of cranes.

Upon the Rocks and in the Moss, grew a Shrub whose fruit was very sweet, full of red juice like Currans, perhaps 'tis the same with the New England Cranberry, or Bear-Berry, (call'd so from the Bears devouring it very greedily;) with which we make Tarts. ["An Account of Several Late Voyages & Discoveries," London, 1694]

German and Dutch settlers in the New World apparently recognized the similarity between the European berries (Vaccinium oxycoccos) and the larger North American variety (V. macrocarpum) and transferred the name. In England, they were marshwort or fenberries, but according to OED the North American berries, and the name, were imported by 1680s and the name was applied to the native species in 18c. The native Algonquian name for the plant is represented by West Abenaki popokwa.