The collection of trace compounds from gaseous media by co-condensation with a major constituent (e.g. water vapour, $\ce{CO2}$, $\ce{N2}$, $\ce{Ar}$) of the matrix.
Source: PAC, 1990, 62, 2167. (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2212 [Terms] [Paper]