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O

O
atomic symbol for oxygen
Os
atomic symbol for osmium
outlier
observation in a series of observations that is so far removed from the rest that it appears to be from a different population or to be caused by a spurious error
out of control
not in a state of statistical control (cf. in control)
output estimate
in a measurement, the value of an output quantity calculated from input estimates using the measurement function
output quantity
quantity in a mathematical model of measurement whose value is obtained by calculation from the values of other quantities, called input quantities
oxidation
loss of one or more electrons by an atom in a chemical reaction, or an increase in its positive valence (cf. reduction)
oxidation-reduction (redox) reaction
chemical reaction in which electrons are transferred between atoms, so that one substance is oxidized and another is reduced
oxidation number (oxidation state)
number that describes the electron density of an atom or ion in a combined state, relative to the electron density in the uncombined state — may be positive or negative
oxidizing agent
1. in an oxidation-reduction reaction, the substance that gains electrons, or is reduced
2. substance, such as O2 or Cl2, that readily takes on electrons