Aerosol describes solid or liquid particles that are suspended within a gas. Example of this are fog and smoke.
Source: Malm, William C. 1999. Introduction to visibility. Cooperative Institute for Research in the Atmosphere. NPS Visibility Program, Colorado State University, Fort Collins, CO: 79 p. As cited in: Hardy, Colin C., Ottmar, Roger D., Peterson, Janice L., Core, John E., and Seamon, Paula. 2001. Smoke Management Guide for Prescribed and Wildland Fire 2001 Edition. Produced by the National Wildfire coordinating Group Fire Use Working Team.