Merodiploid
A merodiploid is a partially diploid bacterium, which has its own chromosome complement and a chromosome fragment introduced by conjugation, transformation or transduction. It can also be defined as an essentially haploid organism that carries a second copy of a part of its genome. The term is derived from the Greek, meros = part, and was originally used to describe both unstable partial diploidy, such as that which occurs briefly in recipients after mating with an Hfr strain, and the stable state, exemplified by F-prime strains. Over time the usage has tended to confine the term to descriptions of stable genetic states. Merodiploidy refers to the partial duplication of chromosomes in a haploid organism.