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Medical Term:


Pronunciation: i-mer′zhŭn


  1. The placing of a body under water or other liquid.
  2. microscopy filling the space between the objective lens and the top of the cover glass with a fluid, such as water or oil, to reduce spheric aberration and increase effective numeric aperture by elimination of refractive effects that result from an air-glass interface; the best resolution is achieved when the space between the condenser lens and the specimen slide is also filled with the fluid.

[L. immergo, pp. -mersus, to dip in (in + mergo)]