Related Terms. Long-term (maturity over 10 years) fixed interest rate debt security issued by a national (federal) government backed by its 'full faith and credit.' Next to treasury bills (maturity less than one year), and treasury notes (maturity one to ten years) T-bonds are the safest form of marketable investment.
bacteria [pl. of bacterium], microscopic unicellular prokaryotic organisms characterized by the lack of a membrane-bound nucleus and membrane-bound organelles. Once considered a part of the plant kingdom, bacteria were eventually placed in a separate kingdom, Monera.
A cluster of Escherichia coli bacteria magnified 10,000 times. A microorganism or microbe is a microscopic organism, which may be single-celled or multicellular. The study of microorganisms is called microbiology, a subject that began with the discovery of microorganisms in the 1670s by Antonie van Leeuwenhoek. Robert Hooke coined the term cell after viewing plant cells under his microscope.