1.NounOn 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.NounThe area defined by the outermost circumference of a tree canopy from where water drips onto the ground.
3.NounA pipe that has small holes at intervals, used to irrigate crops.