prop-free front
Mining
noun
An area in front of a coalface where no props are placed, so as to leave access for a mechanical conveyor, the roof being supported by cantilever bars; the system of supporting a roof in this way.
Origin
1950s.
- by the book
- by the bye
- by the by (or bye)
- by the day
- by the dozen
- by the grace of God
- by the gross
- by the head
- by the minute
- by themselves
- by the numbers
- by the same (or that or this) token
- by the same token
- by the skin of one's teeth
- by the sweat of one's brow
- by the truckload
- by the way
- by-the-wind sailor
- by the yard
- Bytom
- bytownite
- by turns
- byun
- by water
- byway