Noun, pl. prokaryotes
1. Any of the group of organisms primarily characterized by the lack of true nucleus and other membrane-bound cell compartments: such as mitochondria and chloroplasts, and by the possession of a single loop of stable chromosomal DNA in the nucleiod region and cytoplasmic structures, such as plasma membrane, vacuoles, primitive cytoskeleton, and ribosomes.
2. Group of organisms, mostly unicellular, whose cells lack a cell nucleus (karyon). (wikipedia.com)
Word origin: from the Greek πρό- (pro-) “before” + καρυόν (karyon) “nut or kernel”