I. ˈkrakə(r)z noun plural but singular or plural in construction
Etymology: so called from the cracking noise produced by the seeds when the berries are eaten
: black huckleberry
II. adjective
Etymology: from plural of cracker (influenced in meaning by cracked, crackbrain )
slang Britain : crazy
I'm here to tell you that you're driving me crackers — Noel Coward
also : intensely enthusiastic : cracked
we went crackers about them — Clarence Woodbury