I. ˈrä-z ə n, ˈrȯ-, dialect ˈrȯ-zəm noun
Etymology: Middle English, from Anglo-French reisine, rosine resin
Date: 13th century
: a translucent amber-colored to almost black brittle friable resin that is obtained from the oleoresin or deadwood of pine trees or from tall oil and used especially in making varnish
II. transitive verb
( ros·ined ; ros·in·ing ˈräz-niŋ, ˈrȯz-; ˈrä-z ə n-iŋ, ˈrȯ-)
Date: 15th century
: to rub or treat (as the bow of a violin) with rosin