Medical Definition of colloid
1: a gelatinous or mucinous substance found in tissues in disease or normally (as in the thyroid)
2a: a substance consisting of particles that are dispersed throughout another substance and are too small for resolution with an ordinary light microscope but are incapable of passing through a semipermeable membraneb: a mixture (as smoke) consisting of a colloid together with the medium in which it is dispersed
Seen and Heard
What made you want to look up colloid? Please tell us where you read or heard it (including the quote, if possible).