balsam fir, common name for the evergreen tree Abies balsamea of NE North American boreal forests. It has small needles and cones and is used for lumber. It is also called Canada balsam, as is the resin it produces, which is used as an adhesive in optical lenses and glass slides. Balsam fir is classified in the division Pinophyta, class Pinopsida, order Coniferales, family Pinaceae.