drip line

plural drip lines

1. nuclear physicsOn the table of nuclides, the limit beyond which an atomic nucleus will immediately decay by emitting a proton or neutron.

   Hydrogen-7 has so many excess neutrons that it lies beyond the neutron drip line, and will spit out neutrons until it becomes a particle-bound isotope.

2. The area defined by the outermost circumference of a tree canopy from where water drips onto the ground.

   2010, instructions on bottle of Ortho Weed B Gon Max Be particularly careful applying within the drip line of trees and other ornamental species.

3. A pipe that has small holes at intervals, used to irrigate crops.