1British, Scottish dialect The bird cherry, Prunus padus ; (also) the small round astringent fruit of this. Sometimes also (perhaps by confusion): any of several other trees with small rounded fruit, as the wild cherry, Prunus avium, and the wild service tree, Sorbus torminalis.
2North American rare = "hackberry".
Late 16th century; earliest use found in John Gerard (c1545–1612), herbalist. Probably the reflex of a borrowing from early Scandinavian (compare Danish haegebaer (already in early modern Danish), Norwegian heggebaer, Old Swedish hägbär (Swedish häggbär)) from the Scandinavian base of Old Icelandic heggr bird-cherry tree + the Scandinavian base of Old Icelandic ber, with remodelling of the second element after berry; in form hagberry probably also with remodelling after hag.