Abutment

noun

1. The point of junction between two things, in particular a support, that abuts.
2. The solid portion of a structure that supports the lateral pressure of an arch or vault.
3. A construction that supports the ends of a bridge; a structure that anchors the cables on a suspension bridge.
4. The part of a valley or canyon wall against which a dam is constructed.

   "Heavy rains have caused the dam's abutments to seep, raising concern over possible dam failure."

5. Something that abuts, or on which something abuts.