imbibition

The process by which a substance absorbs a liquid and, as a consequence, swells in volume but does not dissolve. Imbibition, which is usually reversible, is exhibited by many biological compounds, particularly by cell-wall constituents such as pectin, celluloses, and lignin. The testas of dehydrated seeds imbibe water just prior to germination and the process is also important in water uptake by roots. See also matric potential.