Skip to Content
Medical Term:


Pronunciation: i-mer'zhun


  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)]

© Copyright 2017 Wolters Kluwer. All Rights Reserved. Review Date: Sep 19, 2016.