hackberry: any of various trees of the genus Celtis having inconspicuous flowers and small berrylike fruits
tree: a tall perennial woody plant having a main trunk and branches forming a distinct elevated crown; includes both gymnosperms and angiosperms
gabapentin: an anticonvulsant (trade name Neurontin) used to control some types of seizures in the treatment of epilepsy; also used to manage neuralgia caused by shingles