The Collaborative International Dictionary
crossing guard \cross"ing guard`\, n. a person who stands at a street crossing to assist children to cross the street safely; -- usually used near schools during the times that children are entering or leaving the school.
Note: Crossing guards may be employed by a municipality as auxiliary police officers, or may be unpaid volunteers. Some wear uniforms, others do not. They are commonly older citizens who are retired or not employed full-time at other tasks. At some schools, older students from the school are trained to perform the function of crossing guards.
Wiktionary
n. A person who directs vehicular traffic so that pedestrians, especially students, may cross the right of way.
WordNet
n. someone who helps people (especially children) at a traffic crossing
Wikipedia
A crossing guard ( United States, Canada and India), a school crossing patrol officer ( United Kingdom), school crossing supervisor and sometimes guard ( Australia) or school road patrol and guard ( New Zealand) is a traffic management volunteer who is normally stationed on busy roadways to aid pedestrians. Often associated with elementary school children, crossing guards to stop the flow of traffic so pedestrians may cross an intersection. Crossing guards are known by a variety of names, the most widely used in the United Kingdom and Australia being "lollipop lady/man", a reference to the large signs used that resemble lollipops.
Usage examples of "crossing guard".
Nothing except for these old scars the crossing guard gave you, and that was over two years ago.
If the ATTF operated the way the NYPD did, we'd all be transferred to school crossing guard duty.
When she heard Entragian coming after them-that big, powerful engine- she spun around and held her hands up like she was a crossing guard or something.
There were eleven physicians and surgeons at the reunion, one ex-governor, two state senators, a locomotive engineer, and a crossing guard.