1) A regional word for the elder.
1423-4 usque ad quamdam veterem arborem vocatam Burtre versus le Kyrkestiyll, York
c.1530 lyyng on the Flatte at the Burtre, Catterton. It was first recorded in minor place-names: c.1200 unam [acram] in Buirtrekelde, Marton in Cleveland
n.d. ‘one and a half roods at Burtrebusk’, Barforth
1642 ‘a certain close called Burtry Close’, Thirsk.