What is end bearing?

There are multiple uses of the term in the construction field, but end bearing is a term which usually specifies that a member (a floor joist for example) is resting on or abuting a vertical member (a load bearing wall for example). The more the end bearing (the area of vertical wall contacting the separate member) the more the load can be distributed evenly.

In the example given, if the horizontal member supported more weight than the end bearing capacity, it could crush the sill of the load bearing wall and cause the system to fail.