different between treadboard vs nosing

English

tread +? board

treadboard (plural treadboards)

nosing

nosing (plural nosings)

An animal's pushing or exploration with the nose.
- 1982, Dave Hughes, An Angler's Astoria
  The hours of the day often follow such a beginning like a wagging tail follows through the nosings and affections and fireside dreamings of a happy dog.
That part of the treadboard of a stair that projects over the riser.
Any similar projection, such as the projecting edge of a moulding.

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